One of the artists I watch here on DeviantArt lost many years' worth of photos when the hard drive crashed. They weren't backed up. So this is a sort of "public service announcement" to remind you that computer hard drives do fail. What will you do when that happens? And yes, I use the word "when" not "if".
I keep my entire collection of photos, which also includes scanned copies of prints, on three different computers. Plus, I've burned a couple of DVDs with photos. I also keep the more recent ones on a flash drive, although that's more for synchronizing the computers than anything else.
Another tool that I use to help synchronize recent photos is Dropbox
, which is online storage. I manage to keep about one year's worth of photos on my free and limited Dropbox account. Anything older than one year I'll remove from that folder to make room for new photos. (So I keep the Dropbox folder separate from my folder of photos and copy between the two.) If you click through that Dropbox link
and open an account, we'll both get an extra 500MB of storage. The Basic membership level is free, and for $10 per month you can get 100GB if you like it.
Google drive offers online storage, as well. I've not used it for archiving or synchronizing photos, however. I prefer it for it's ability to edit and share "Office-like" documents, so I don't want to clutter it up with photos.
There are other free online storage sites, such as OneDrive, Box and iCloud. Here's a recent CNet article that compares seven free cloud services.
And, in a pinch, simply e-mailing a few photos to yourself is effective.
The saying "failing to plan is planning to fail" applies so well in this context. Don't let it apply to you!
New Edit: I just created an account with Barracuda Network's Copy. Here's a Referral Link
that you can use. If you join copy using the link we'll both get an extra 5GB of storage space!