Bushbandit,
I use and recommend a free program called Keepass :
http://keepass.info/ (NB - NOT .com)
It's a "password safe" program - you create a new database file that's encrypted and locked with your master password. Inside, you can store all your forum logons, your back account details, TFN - pretty much anything and everything you want access to. We use it at work to store system passwords as well as emergency contact details.
You can set it up with Dropbox (also free) to synchronise your database file across multiple computers and devices. I have it set up to synchronise my database file between my work and home PCs, as well as the phone and iPad. I've got a paid ($2, from memory) iPhone/iPad app called Kypass (
https://itunes.apple.com/au/app/kypass/id425680960?mt=8) on my iphone and ipad which works beautifully.
The end result is that if I'm travelling I've got easy access to all my personal info on either the phone, iPad or laptop. It's all secured and encrypted. Works really well. That's how I do it.
The other option would be to save your database file to a USB key as you've said - that would work too. Just a bit more manual than the automatic syncing option, and means that if you accidentally lose the USB then you're in deep trouble.
Happy to answer any other questions about it. I'm sure there's other options out there that are just as good (such as Noel's suggestion), this is just the one that I'm familiar with and have had great results with. Initially I was sceptical, but I wouldn't be without it now. Any option is going to be much, much better than carrying around the book like you do now.
Good luck,
Matto