I used to use a regular money clip to hold my cash and credit cards. I found that when you have a big wad of notes and four or five credit cards, it becomes overfilled and everything pops out. As you spend your money, you eventually get a to a sweet spot where everything fits nicely. You then start running out of money and it all gets a bit loose. The only way to deal with this was to keep bending the clip as the wad changed size.
I read this tip in lifehacker a while back about money clips. Basically, after a bit of tinkering, you would end up with a money clip that could hold some flat keys as well. I'm a little lazier than that and hence would never bother with making something, but I liked one piece of this post, namely the bulldog clip.
After reading this post, I put aside my nice Tiffany money clip and got all utilitarian. I took the basic element and simply used a bulldog clip instead. The beauty of this is that you can choose the size you want depending on the amount of cards and cash you like to carry around with you and then it adapts nicely as you spend and draw out cash. It is far superior to a simple money clip!
It also costs next to nothing. Long live the bulldog clip!