Some stores (like Barnes & Noble, Modells, Hallmark, supermarkets) will access your membership info via your telephone # so it is not necessary to carry all of those cards.

Many stores provide smaller ID tags for a keyring. You could keep a separate keyring just for these and if you have one, then leave it in your car, perhaps.

If you have a car....

For places I don't shop at regularly, I keep a vinyl Business Card holder in my car for regular size membership cards and access them as needed.

Another "leave in car" option is to keep these cards in a visor organizer (under $5. at Walmart). These have storage pockets. Here's an example:

http://www.containerstore.com/browse/Product.jhtml?PRODID=10012092&CAT ID=259

Store credits/giftcards (items with monetary value) are kept in my wallet.

For all those store "preferred customer cards," here's what I do. Most of them I put on a keyring. For cards I use frequently that didn't offer a keyring version, I punch a hole in the corner (away from the bar code or swipey strip).
In my purse, I also carry a small rectangular zip pouch that I carry coupons, receipts, paint chips, etc. in, and I tuck in most of the other cards I have and the Bed Bath & Beyond 20%-off coupons (I never shop there without one!).

Sometimes I'm tempted to just leave that pouch in the glove compartment (as long as none of those receipts have my full credit card number on them!), so it's there if I need it. Always happens that if I leave the pouch at home, that'll be the time that I need something in it.

We've actually ended up using the key ring mini cards with the kids. When I send them to the store to get bread or something, they already have the rewards card on the key ring for their bike locks.

It seems like I carry more cards for things like health insurance ID, AAA, library card, car insurance, etc. So two credit cards and two grocery cards are in an outside zippered compartment of my purse and all of the other cards are kept where most people would have a wallet. I dislike having to pull all of that out when I just use the same two cards all of the time.

Gloria

My mom, who still does all her shopping only on a certain day of the week, will sit down the night before and gather whatever she needs for the store she plans to visit. That wouldn't work for me. For example, I usually do drug store shopping on days when rush hour traffic doesn't have me already running behind. If traffic is heavy, I'll wait until another day to stop at the drug store.

I searched for 'credit card pouch' and found a picture of something like it.

So, you send all your bar codes to this guy and he puts them onto one card?

It's easier than that! You enter your numbers from your club cards into the form on the website, select a store from the drop down menu, then print out your own card.

I printed it on card stock paper, cut it out on the dotted lines, folded it in half. Now I have 4 bar codes on one side 4 on the other. Being anal, I felt good about it because you can have 8 accounts per card and I had 4 grocery stores and 4 others.

Took me 10 minutes tops.