I use a Samsonite business card holder similar to this one for loose HuCards. Sorry for the horrible cell phone pics!
I went the collectible card 3-ring binder route. I picked up the sheets and the cheapest hard cover 3-ring binder at Target. Please excuse the horrible masking job on the images. I cranked these out really quickly.
Here's the front of the binder. I found the logos online and printed them out on an 8.5"x11" sheet of paper.
And here it is open. I added a little Scotch tape flap to the top layer because they kept wanting to slide out. I love being able to see the artwork on the chips. US gamers got robbed. I need more PCE HuCards.
Behind the card sheets are sheets I found at one of the big office stores (I forget which one) that hold manuals for games I don't have cases for. I think I originally read about these sleeves from the old Turbo Mailing List. I think they are designed to hold audio cd covers for the folks who keep their audio cds in binders.
Those credit card sleeves that can be found on eBay are awesome for when I take the Express out. Most of my games came with a sleeve but it was nice to get enough to cover my remaining games and have enough for games to come (or to give away to friends that need 'em) for only a couple of bucks.