3T do an alloy bar that 'rises' from the bottom but is flat along the top, and Crank Bros do a range of bars which are only just risers
There's a few that are flat along the top now, I've got a pair of Bontrager "Big Sweep" bars kicking about I was going to try, but at 640mm they're a bit narrow now I've gone up to 720mm on my full sus!
In fact i'm thinking of getting some of those Sunline 762's. I love my V1 19mm risers, only now I've got used to running a lower front end on my HT, and I can't physically drop the stem any more on my full sus, some flat bars might get the position I want on it. Shame they're over £50 for some ally bars!!!
Oh and the Crank Bros bars are apparently an 8mm rise, which is about as low as it gets without quite being flat. But they're only a maximum 680mm wide sadly. Raceface do a couple of bars (Atlas FR and the Deus) that come in a 1/2" rise too (so 12.7mm) which have a very nice sweep and shape.