I've used a Defender bellyband from www.action-direct.com for deep concealment for quite some time. I have gotten away from the bellyband somewhat of late due to finding some holsters that work well for me, but I still use it when the situation calls for it. I used it on the vacation this past week as I had several different pistols with me, and it works well with all of them.
I have often thought about using an elastic band in conjunction with a holster for CCW as this would combine the good points of the bellyband (weight distribution, tuckable, no hooks or loops on the belt) with a holster (easier to reholster, better fit to particular weapon).
I just found such a product. It is from Horseshoe Leather.