How Do You Track Patterns?

Every time there's a pattern sale and I'm looking through the books to see what patterns I might want to pick up, I find myself once again trying to figure a system for keeping track of what patterns I already own. In particular, I need to figure out some system I can take with me to the store (so just having a list of them on my computer at home won't work).

Anyone out there got a system they'd like to share?

ETA:
I didn't originally think to mention that I don't have a smartphone. So any system that requires web access or an app won't work. But I do like the idea of photos, and was thinking of going that route (I just wasn't sure if maybe that was overboard), so I'm glad to hear that works well for some folks. So my plan is to take photos (or grab images off the web) and keep them all in a separate iPhoto library. I'll name them for pattern company and number, and tag for things like type of garment (dress, shirt, etc.) style details (v-neck, empire waist, etc.) and whatever else I can think of. So then, when at home, I can easily search/sort for whatever I'm looking for.

For taking with me to the fabric store... I'm going to look into syncing the iPhoto library with my iPod, as one person mentioned they do. Not sure that will work, as my iPod is an older model. So if not, then I'll just print out pages of thumbnails and/or a simple list by pattern number that I can take with me.

Thanks to everyone for sharing their methods/ideas.