I use my Canon 7D quite a bit as a second camera, the cumbersome menus and strange ergonomics make it difficult to use as an A camera on any jobs. Of course the impossible audio also tends to relegate it to MOS roles. usually I end up using it for timelapse, B roll in tight places, B roll with limited field of focus, and sometimes a second angle on interviews.
I've found two products that actually make the camera function quite a bit better.
Finally Magic Lantern has got their software hack up and running for the 7D so that it comes up with only a push on the garbage can button, booting from the card. The raw recording mode is still a bit strange as it can't offer resolutions or frame rates I want.... no doubt this is because of limits in the card and electronics. Using raw for the first time ever I managed to shut down the camera from overheating. Nice to have VU meters on screen and some albeit awkward control of audio levels. This hack also includes a very nice and easy to use timelapse.
The second is the $300 filter from Mosaic Engineering, that virtually eliminates the horrible moire problem in the 7D This thing is a must have!!! very little effect on resolution even on wide prime lenses. This makes the 7D image competitive with the much higher price full frame digital cine cameras from Panasonic and Sony.