I came across NASA Federal Credit Union today as well. Their website is a bit sparse and confusing, but it appears they may offer 0.4% on checking, with no fees if you maintain a $2,500 balance. That's as high as my current online savings account (albeit, not the best savings rate one can get), so if they don't cap the balance that gets interest, it might be a good candidate for what I'm looking for. They also offer shared branching with no fees, which is a benefit as I have several potential shared branches local to me.
I've got an email in to their support clarifying the maximum balance that can receive that interest rate. Same question - any experiences to share with this one?