Well I use Flickr.com to store my photos (i almost always make them PRIVATE). But apart from that:
1. Windows Live SkyDrive seems to be ok :) 1GB is ok for me, although I wish they would merge the SkyDrive storage with Hotmail storage. But other than that, it seems just fine.
2. Xdrive is good. really good. BUT you have to have special software installed in order to upload.
Well it basicly just goes on. There are online storages you pay for - which turn out not so good. But myopinion is that SkyDrive is near the best: it doesn't use special software - just your WinLive ID. Other than that, I haven't experimented a lot.