One of the easiest services I use for backing up is Dropbox. They give me a folder to store documents in and it automatically pushes a copy of those documents into the cloud (be sure to use a great password) and syncs them with my other computer; so I’ve automatically got 3 copies of the file now. I can view these files from anywhere on the internet with a web browser or with my iPhone, iPad or an Android device. If I store photos from my iPhone to Dropbox it’s now in the cloud and on my two syncing computers (and on my iPhone).
DropBox will give you 2 GB (more than 3 CDs of storage) for free. 
Dropbox syncs that storage with your computers plus you can view with your Android and iOS devices. Are you always sharing certain documents with a co-worker or friend? You can have a shared synchronized folder between your computers. You can even share specific photo albums via the web with friends. If you’ve got your computer synced you don’t even need to be on the internet, those files are there on the computer, if you change, add or delete any files the next time you connect it will sync everything automatically for you.
And if you get more friends to sign up (and install it) they’ll give you more free space (so please use my link for extra space). It runs on Macintosh and on Windows, the programs and apps are free! Not only do I get 500MB for free if you sign up if you follow my link, so do you (you get 500MB extra for following my link verses no bonus on your own!).
They make it incredibly easy to share photos with others, even just via their web site. You got a folder, you share the link and you’ve got a photo album shared. Super super easy.
3 GB of bonus space: After you sign up, they will then let you import directly from your camera and give you an extra 3 GB (that’s 5 GB total, about 8 CDs of back up!). This camera imports directly from you camera and from chips, it’ll also import automagically from your iPhone or other iOS device when you plug it into the computer. Even if you don’t want this feature, import in 3 GB of photos and video and then delete them, you’ll still have the space (as far as I can tell all this free space is for life). As far as I can tell, after getting the 3 GB free you can delete the photos, turn off the upload and keep the 3 GB of space…
Tip: To get more use out of all that storage, once you get a few GB of photos into the cloud, back them up to a DVD (standard DVD’s hold more than 4 GB) and make multiple copies. Keep a copy at your Mom’s house or at your kids house or in your safe deposit box. You don’t want all the copies at the same place in case there is a fire and they all burn down. Then you can delete these photos from the cloud and you’ve got more space for more photos.
Advanced features: You have options to not sync certain folders with dropbox, so if you don’t have the 5 GB of extra space on your laptop you don’t need to keep every folder synced with your netbook or MacBook Air. You could just sync your documents folder and recent photos and not worry about everything else.
Don’t like: The one thing I don’t like about the Dropbox photo import is they rename your photos with the date and time. I actually like the date and time part but I wish they just added that to the original file name, it’s hard to tell where the duplicates are with completely different filenames. But I can decide if that is important later, it’s the 3 GB of extra storage that I want for free, I can use it for anything I want later…
Another tip: Whenever I buy a new product, I try to go on-line and get the digital version of the manual for it, then I put all these documents in a folder in the cloud somewhere. Then no matter where I go, I have the manual for that computer, digital camera, car stereo, GPS unit or anything that I might be traveling with. On the other hand, I also have the manual for my stereo and stove with me too, I don’t really need those all the time, but it’s nice to have those manuals easily accessible when I need them.
