I was asking myself this question last month....
Supatrigga will let you do some fancy stutter type stuff if you can control it properly...

Then there are always cool filters you can drop on the whole mix to do some wacked out beat-sync'd shit with lfo shapes or sample & hold... etc
Can't think of any plugins offhand as I used my Alesis Philtre..

But a Moogerfooger MF105 w/ tap tempo would be phaaaaaaaaaat