With flexible tools for searching, organizing, sharing research, and creating bibliographies, the EndNote for iPad app extends your ability to stay on top of cutting edge research and connect with your EndNote library on the go. If you've set up your personal account on www.myendnoteweb.com, you can also access your content there from any mobile device.
The mobile version of zotero.org allows you to access and edit your Zotero library on your tablet or mobile phone. While there are no official Zotero apps for mobile devices, there are several third party solutions listed on this site.
Mendeley is a free reference manager and academic social network. Make your own fully-searchable library in seconds, cite as you write, and read and annotate your PDFs on any device. Showcase your work on your profile and assess the impact of your research. The app is available for both iOS and Android.