What I've found helps is to get a good handheld PDA and store copies of your most important information on it (ie. handy lists, idea inspiration files, useful addresses, e-books, MP3s, PDA games, mini-movies, etc.).
Then get a nondescript but durable wallet you like and velcro your PDA inside so it's nice and secure.
Then put all the usual things you normally store inside a wallet (money, credit cards, etc.). Other things you might additionally store in it (especially if it also has a zippered compartment or a snap coin area) include SD cards, mini bud headphones, jump drives, and one of those pens that also have a flashlight capability.
If you get a wider wallet, in many cases you can also velcro a separate MP3 player inside or your cellphone (if it's not too thick).
Voila! Now in less than the space (or the weight) of a DayRunner you can carry a buttload of useful information with you, as well as tons of applications to help keep you busy/entertained if you get stuck waiting in line.
If your wallet doesn't have finished holes/grommets that will let you wear it as a purse, you can either carefully punch a couple of holes in the wallet so you can, or you can carry it like a small clutch.
I get my wallets at the thrift shop for $2 or less. A very cheap solution.
When I need to get more elaborate, I just carry my laptop backpack and throw the wallet / secret PDA holder inside.
_________________
?How I wish that somewhere there existed an island for those who are wise and of good will.?--Albert Einstein
INTJ.