usually with my band, if we feel like we aint getting something cool, we do some practices we picked up here and then.
-always play just the first beat of a bar together. (without a metronome, looking each other, stomping your feet to the ground or whatever)
when your good at that, you might go for 2 bars, 3 bars then, 3000 bars?
then try other beats (third eight for example)
swing and straight
-kinda the same: have a metronome playing on different beats and also play the one together.
-funny thing i was shown in a workshop with some french rockband:
all of you play the first beat of a bar, but everyone has different time measures.
first guy plays 3s, secound 4s, others 5 and 7.
this can be real funny and you can do all this stuff drunk and with no instruments 8)