Twitter-icon.com has a great selection of twitter icons and buttons.
Site: apuntatelo.com.ar (Apuntatelo - Tu link-sharing de apuntes)
Apuntatelo es el primer link-sharing dedicado al intercambio de material estudiantil y cultural. No importa de que facultad seas, todos podemos compartir.
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!