Get a Gmail account or other secure web-based email. Then scan your passport bio page, visas, birth cert, eyeglass/contacts prescription, and anything else you might conceivable need and email the scans to that account.

Then if you lose your passport, break your glasses, etc. etc. you can have your documention as close as the nearest internet access.

Some will say you shouldn't put all that on the Internet, but there isn't really all that much information on those documents, and a reputable service like gmail is going to have good security - that's how they stay reputable - so I think the benefits far outweigh any possible drawbacks.