Again, thanks for more great suggestions. Still haven't bought anything yet, as I've been waffling on getting just a larger bag overall that can also hold all my cables, rather than a small accessory bag for just the cables. The front runner right now for an accessory bag is the jumper cable bag from eBay I linked back on the first page.
I wish these guys kept their stock current - I've bought from them several times and their bags beat anything out there for rugged quality. I own the "mid-range bag" as my work briefcase, but the Tac-Pad would be perfect for this use. The Responder II Pouch would also work but it's a bit pricier.
http://www.countycomm.com/bags.html