Zotero now works with Internet Explorer, iPads, and other mobile browsers. Use the Zotero Bookmarklet to save sources directly to your Zotero library online. You must have a (free) Zotero account, but no other software installation is needed.
Zotero users now also have access to 300MB of free storage (for PDF’s and other attachments, upgraded from 100MB). More details here.
What is Zotero?