Twitter-icon.com has a great selection of twitter icons and buttons.
Site: nopcommerce.com (NopCommerce - open source shopping cart.)
nopCommerce is the open-source eCommerce solution. nopCommerce is available for free. It has everything you need to get started in selling physical and digital goods over the internet.
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!