If you just want to store stuff online, you can use DropBox or something (even S3). WebDav isn't really used by many applications these days, so you don't really need to worry about filling up the space (and OmniFocus doesn't take up much space at all, so I wouldn't worry about filling up 2GB with just OmniFocus).
If you do like the look of DropBox, feel free to share the love with me and my shameless referral link:
https://www.getdropbox.com/referrals/NTE5NjgwOQ