there are a few different versions of slide 2 unlock.
The current version of S2U2 is .86 (My opinion, that this one is the best out)
http://forum.xda-developers.com/showthread.php?t=343256
There is also Slide2Unlock Pro v1.03.1126
http://forum.xda-developers.com/showthread.php?t=350842
There is a ppcgeeks version but i dont think it was updated in a while.
There are also a few more i have seen floating around.
Here is S2U2 v.86 with an htc theme.