Ha! A nightlife in Orlando!?! Sadly thanks to Mayor Hood and former Orange Cnty Commisioner Chapin, our once thriving and internationally known club/bar scene died about 5 years ago. They instituted a 2am closing time, wich kind of limits ones nightlife.
As a former raver and clubber, let me tell you what constitutes as clubs around here leave something to be desired. The groove at citywalk is one of the few places I'll go. Xs at Point Orlando is alright, as are the other new clubs there metropolis/matrix. I recommend skipping pleasure island. If downtown isn't too far away for your tastes, hit up orange ave, orlando's main club corridor.
It all depends on what kind of music/atmosphere you're lookin for. If you let me know exactly what you're into, I might be able to give you some info.