Nice list and looking to add to it.

1. Yeah, Windows is great… I used it to download Linux.
2. A fool and his money are soon venture capital.
3. If Windows is the answer, it must have been a stupid question. — Filip Van Raemdonck
4. No trees were destroyed in the sending of this message, however, a significant number of electrons were terribly inconveniencd.
5. Infinite loop: see ‘Loop, infinite’. Loop, infinite: see ‘Infinite loop’. — Luca De Vitis
6. There are only 10 types of people in this world… those who understand binary, and those who don’t.
7. If God had intended for email to be written in HTML, then the traditional signoff of prayers would be — Tom Liston
8. No .sig for you! NEXT!
9. Using the internet as it was originally intended… for the further research of pipebombs.
10. : Every cloud has a silver lining (except for the mushroom shaped ones, which have a lining of Iridium & Strontium 90) — Sean Dwyer
11. My other computer is your Windows box. — Shot (Piotr Szotkowski)
12. Only 10% are Mac users. But remember, we’re the top 10%
13. Sendmail administration is not black magic. There are legitimate technical reasons why it requires the sacrifice of a live chicken.
14. There are two rules for success: 1. Never tell everything you know. — Tobias Toedter
15. A Microsoft Certified System Engineer is to information technology as a McDonalds Certified Food Specialist is to the culinary arts — Michael Bacarella
16. Hi! I’m a .signature virus. Copy me into your ~/.signature to help me spread!
17. find / -user your -name base -print | xargs chown us:us
18. Sendmail is like emacs: A nice operating system, but missing an editor and a MTA
19. 90% of statistics are made up on the spot.
20. Contentsofsignaturemaysettleduringshipping. — Mike Beattie
21. Differences are good. If two people agree, one of them is redundant — Brian White
22. This message was brought to you by the numbers 0 and 1.
23. A mathematician is a machine for converting coffee into theorems.
24. Instead try to realize, that there is no sig.
25. Long noun chains don’t automatically imply security. — Bruce Schneier
26. C:\DOS. C:\DOS RUN. RUN DOS RUN
27. I love deadlines. I like the whooshing sound they make as they fly by — Douglas Adams
28. Never underestimate the power of very stupid people in large groups — Mike Beattie
29. “In the beginning was the word, and the word was content-type: text/plain” – Martin Schulze
30. That which does not kill me makes me stronger. That which does kill me I’ll deal with when I respawn.
31. It’s not denial. I’m just selective about the reality I accept. — Bill Watterson
32. Anyone who quotes me in their sig is an idiot — Rusty Russell
33. Real men send email in plain text
34. scp $FAV_RESTAURANT:$FAV_FOOD /dev/stomach
35. Microsoft is to operating systems & security …. …. what McDonalds is to gourmet cooking.
36. A mouse is a device used to point at the xterm you want to type in.
37. When an engineer says that something can’t be done, it’s a code phrase that means it’s not fun to do.
38. “Emacs is a nice OS, but to compete with Linux or Windows it needs a better text editor” — Alexander Duscheleit
39. If it’s not broken, let’s fix it till it is.
40. Nothing screams poor workmanship more than wrinkles in the duct tape
41. A polar bear is a rectangular bear after a coordinate transform.
42. If you play the Windows2000 CD backwards, you get a satanic message. If you play it forwards, it installs Windows2000!
43. I used to have a sig, but it took up too much space so I got rid of it!
44. I am root. If you see me laughing, you better have a backup!
45. Somewhere, there is a .sig so funny that reading it will cause an aneurism. This is not that .sig.
46. Microsoft – “Where do you want to go today?” Translation – “Let us take you for a ride.”
47. Any sufficiently advanced bug is indistinguishable from a feature.
48. Experience is what you get when you didn’t get what you wanted.
49. I’ve already told you more than I know.
50. To understand recursion, we must first understand recursion
51. checkuary, n: The thirteenth month of the year. Begins New Year’s Day and ends when a person stops absentmindedly writing the old year on his checks.
52. The following is only a sig. The preceding is only a disclaimer.
53. Be incomprehensible. If they can’t understand you, they can’t disagree with you.
54. People replying to my sig annoy me. That’s why I change it all the time.
55. “I have not failed. I’ve just found 10,000 ways that won’t work.” –Thomas Edison
56. Sigmentation fault. Comment dumped.
57. This is not a sig. I am too lazy to steal one, perhaps you could loan me yours?
58. I lost my .sig in the ashtray…
59. [dpkg] We are the apt. Resistance is futile. You will be packaged.
60. A bus station is where a bus stops. A train station is where a train stops. On my desk, I have a work station…
61. If at first you don’t succeed, give up skydiving
62. When the going gets weird, the weird turn pro.
63. Getting rid of all the bad in the world, one lawyer at a time…
64. All things are possible, except skiing thru a revolving door.
65. Enjoy your job, make lots of money, work within the law. Choose any two.
66. “In theory, there’s no difference between theory and practice. But, in practice, there is.” – Flash Gordon, M.D.
67. Lead me not into temptation, for I can find it myself
68. Sig Removed Due To Utter Lameness
69. The problem with making computers complete idiots can use is you have complete idiots using computers.
70. All social problems have a technical solution. That solution may or may not be socially acceptable.
71. “easy as 3.141592653589793238462643383279502884”
72. I had a sig, but it didn’t want to be seen with me, so I chain it to every post now
73. The above was written as part of an attempt to waste time
74. I’d have a really cool .sig, but right now I can’t even remember my own damn name.
75. This sig temporarily on hiatus for retooling.
76. This is not a sig. It may look like a sig, but trust me, it’s not.
77. Kaa’s Law: In any sufficiently large group of people most are idiots.
78. “In spite of everything, I still believe that people are really good at heart.” – Anne Frank
79. To decode this comment into a readable form, rot13 it twice.
80. “Begin at the beginning”, the King said gravely, “and go on till you come to the end: then stop.”
81. Quidquid latine dictum sit, altum viditur. Whatever is said in Latin sounds profound.
82. load “linux”,8,1
83. The most stable NT box is the one that is powered down and filled with concrete.
84. I used to have a tasty sig. But I ate it.
85. DTA – Death To Acronyms
86. [Connection closed by foreign host]
87. C:\WINNT\SYSTEM32>tracert life.liberty.pursuit-of-happiness
88. And lead us not into temptation, but deliver us some e-mail
89. Microsoft may not be the / of all evil but it is not for lack of trying
90. This is just a test…….. if this was an actual sig, you would have been mildly amused……….
91. Let’s call it an accidental feature. — Larry Wall
92. If ignorance is bliss, wipe the smile off my face
93. I’ll get a cell phone when they prise it into my cold, dead fingers.
94. NO CARRIER
95. This post uses only 100% recycled electrons.
96. (Disclaimer: This is a joke. If you have a serious response to this post, please seek professional help. And don’t drink so much coffee.)
97. If it was said on slashdot, it MUST be true!
98. Microsoft: What do you want to reinstall today?

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List first found at: http://www.jubed.com/jokes/view/98-best-email-signatures-for-geeks/