For hosting common files it's ok. Also it is on Android too do, great to transfer files between your Windows and your phone. But if you want better security you have to subscribe a monthly offer.
miniPaint - Online graphics editing tool use HTML5 technologies like Canvas, Offline support, Drag and Drop.
Dropbox - Online Sync and File Sharing
RealWorld Paint - RealWorld Paint is an free portable image/photo/animation editor.
Google Drive - Access and sync your files anywhere
Paint XP for Windows 7 - Standalone old MS Paint program that allows you to get your old XP Paint interface in Windows 7.
Mega - Secure File Storage and collaboration