To be honest I'm surprised it's taken this long for the big companies to offer this sort of service.
Odd isn't it that people see Google as always leading the way when MS and Apple, as well as Dropbox, box.net etc have been doing this for years.
I've settled on a mix of Drobox (for integrated into mobile apps stuff) and SkyDrive atm. SkyDrive in particular been updated with some quite impressive Windows, iOS, Mac and WP Apps. 25Gb free storage and integrates into explorer (at least in Windows) so it just appears like normal storage for drag and drop goodness as well as file sync, selective sharing and remote access etc.
I quite like that you get access to the Office web apps (Word, Excel, Powerpoint and Onenote) free as well on-line.
https://apps.live.com/skydrive
If you already have a Skydrive (Hotmail/Live/ etc) account you need to log in and make sure you tick the "free upgrade for existing users" to 25Gb before May though, looks like by default it'll be 7Gb free going forward.
Unsurprisingly no native support for Android, you have to go through the browser.
**edit**
Sorry, hadn't seen the SkyDrive thread further down the page so I've duplicated stuff around the Apps etc here - doh!