LOL - I think I'd say Pendulum are almost the complete opposite of a drum circle... They also never change drum beats (except for one bar in "Fasten your seat belts".
If you're looking for rhythmic/time-signature changes, you could look into Shpongle. Sort of trippy, floaty music but lots of interesting time signaturesm and metric modulation (sometimes even super-imposed metric modulation

) 6:8 -> 4:4, lots of 7:8 and the like.
Or Tool, but again, that's a very different genre - but lots of interesting time signatures/changtes
Just drum-tracks though, nothing springs to mind. Mind you, I generally hate drum cirlces (and I'm a drummer)