Zotero: Install Zotero
for iPad

You can use Zotero on the iPad browser by installing a "Bookmarklet," a special link that saves items directly to your Zotero account on the web.

You must have a Zotero account, and your iPad must be online, to use Zotero.

1. Open zotero.org/downloadbookmarklet in iPad Safari and bookmark it.
2. Click “iPhone/iPad” and copy the code from the text box on the page.
3. Edit the bookmark you just created.
4. Change the bookmark name to "Save to Zotero".
5. Paste the code from the text box as the URL for the bookmark.

When you're on a page with a citation, select the Save to Zotero bookmark. The iPad browser will save the citation directly to your Zotero library online.

While there is no official Zotero app at present, Zotero's website lists a number of third party apps that work with Zotero.  Most of these apps cost money.

Cross-Platform

Zotero Reader (allows you to view your Zotero library, including attachments, in Android, iPad and desktop)

For iOS 

BibUp (allows you to add books to your library by scanning their ISBN barcodes)

PaperShip (allows you to view and add to your library, read and annotate attachments, and share references)

ZotPad (allows you to view and edit your library, as well as read and annotate attachments).

For Android

Scanner for Zotero (allows you to add books to your library by scanning their ISBN barcodes)

Zandy (view and edit your Zotero library)

Other

Zotfile (a Zotero plugin that syncs your library with your mobile PDF reader and extracts mobile annotations into Zotero notes)

Disclaimer:  This is not an endorsement of any of these products.  Use at your own risk.  We are not able to provide support or answer questions about these apps; users will have to work with the tech support department of each app if they have questions.