I’m not even sure what mine is, but if it’s what I think it is, it’s similar to Ringo’s.
Well, shoot. Apparently I don’t have one.
I use mine far too often, but I’ve been cutting back lately. Probably use it alot because 1) I kind of got in the habit of clicking the Show Sig box, and 2) I have an insatiable need to push my music in other people’s faces. Have been getting better at that once-per-thread thing, though. 
Let’s see if I actually have a sig entered here…
Ditto goes for me.
My sig:
Hmm. I’m not sure I’ve ever used my sig.
Actually, I’m not even sure if I have a sig. Lets see.
I think I have a sig. Let me check.
Mine used to be:
" You have never lied to me, yet I no longer believe you. That is what has disturbed me."
-Nietzsche
But now its:
I’ve changed mine several times and probably will again.
I almost never use mine – but RT’s wit deserves more publicity!
Found this on the SDMB and thought it a screamingly funny put on kind of thingie. Wrote the guy asking to use it as my sig. Got a rather listless, “Yeah sure. Whatever. It’s all pointless anyway,” that I chose to take as an enthusiastic yes.
After adopting, and using, the sig for a while I read some more of the guys posts and discovered it wasn’t a put on at all, he’s actually that depressed.
And then forget to add the sig!!!
I honestly don’t remember what mine is. Oh well, I guess I’ll find out.
My love of “The Matrix” inspired my sig.
[puts the tick in the little box].
I tried to make mine as difficult as I could.
I only rarely use mine, it’s really long and I think a tad on the pretentious side. General rule of thumb for me is only once per thread if I’m going to use it and only if my post is longer than my sig and I remember to click the box. I think I’ve used it all of a dozen times here. I tend to rotate sigs a coupla times a year, if my next one is shorter I’ll probably use it more often.
I don’t remember what mine is, either. Let’s see.
Don’t use my sig often and have changed it several times, but this is the original.
I thought my sig was funny when I imagined it being spoken in a faux-James Bond voice, but when I saw it written out it didn’t seem to work, so I never used it.