I've used the Topeak Compact Handlebar bag with STI levers without any issue. It's small enough that if you tilt it at the recommended angle it won't interfere with the cables. I carry my phone, cable lock, maps, snacks and sunscreen in it without issue. My only knock on it is that the rain cover that comes with it is not very effective. Anything that can't get wet should be bagged.
http://www.topeak.com/2007/products/...ndlebarbag.php
Mark