I'm about to get a Louis Garneau one from my LBS (on order). I hope it proves useful. DH and I have a long-standing battle over who gets to carry the truck keys when we go out for a long ride with the club.
He: "I got 5 pounds of cr*p in my back pockets!!!"
Me: "Sorry, hon. Someone decided women's jerseys (particurlary the summer ones) need only 2 back pockets! And small ones at that. So, I'm all filled up!"
This will allow me to carry the truck keys (not sure if that's a good thing or not, however) and drive back to the shop afterwards when we get back a different times.