I do!!
I have been teaching math in groups since the beginning of second semester and I LOVE it!! We have Harcourt Math--which comes with a ton of resources. When I was teaching whole class, I would feel like I was cheating some of the kids when I would hand them the xeroxed copy of a challenge or reteach page, while giving the rest of the class the colorful, cutesy math pages! Well, when I have small groups it is not a big deal. I also have a projector and interactive white board in my room, I use it daily with my math. I have four groups, a high group, two average groups and a low group. Example of a groups' rotation schedule: I let the high group start out with doing their lesson with the interactive board and Harcourt website lesson, next they do a game, then they come get their worksheet and do it at their seat, last they come to me ( I quickly check their papers and then go into some enrichment lessons--higher order thinking, etc. Lots of times I can use the lesson right in the book, but other times I have to come up with one.) Below I will hopefully explain my groups and rotations (13-15 minutes each)
Group/Rotation schedule
High: board/game/seatwork/teacher
Av1: teacher/seat/board/game
Av2: teacher/seat/game/board
Low: game/*board/teacher/seat
(*if I need to work with the low group longer, they come straight to me for their 2nd rotation)
I also have a rule that they can't go to any rotations until their worksheet is done. I grade them that night (that's the goal

) and have them do any corrections the next morning for morning work.
Hope that helps you! I think it has been more effective!
Melissa