Facebook. If you really don't want others to see your photos you could make a separate Facebook account just for uploading photos. If super high res is something you care about I think Google+ offers slightly better than Facebook. Anything I want super backed up I just upload to Google Drive.
Right now my photos are stored in Trovebox into my personal S3 bucket. I have a script that mirrors down to my local NAS (photo file + meta data from API).<p>My videos are stored in BitCasa's Infinite Drive and a copy is also on my local NAS.<p>Disclaimer: Work @ Trovebox
I use dropbox which I am happy with but I'd love more free space. I like that the app has a passcode on it. I also use G+ backup which honestly freaks me out a little bit. I know they upload private but I check quite often to make sure that they are infact private
HDD + time machine + 2x yearly DVD (one stored offsite at sisters). photos are all we have from years of life - friends don't let friends @#$#@ around with back ups.
Flickr. The Terabyte space is enough for me (though I do have the Pro version) allows me to get the originals again (I think that's for non-pro users too)...and the API is fairly flexible, though I think that's a consequence of it being somewhat neglected...in any case, it's been straightforward to suck down dozens of GB of photos whenever I feel like it.<p>Flickr serves as a pretty good place to share things...lots of random viewers come across my photos...its primary benefit is that it is a great interface for cataloguing and further sorting my photos...especially with geotagging.<p>I've just found out how to link it to Adobe Lightroom, so now even the inconvenience of exporting from Lightroom, then drag-and-drop upload to Flickr has been eliminated.