Twitter-icon.com has a great selection of twitter icons and buttons.
Site: tdl.org (Texas Digital Library)
The Texas Digital Library is a multi-university consortium providing the digital infrastructure to support a fully online scholarly community for institutions of higher education in Texas and the widespread availability of their enormous intellectual capital.
Do you have a twitter account? If so it's important
to get as many people as possible to follow you.
Great follow me icon captures attention of the visitors
and brings more followers to your twitter account.
Choose great twitter icon for you website!