It's also possible to insert an image in the side bar and link it to your twitter account. That's what I tested, being a noob and not knowing much about CSS yet. I will do that for pinterest and facebook as well. Once I get my new logos I will add them this way.
It would be awesome if the image for each widget could be customized though. I would also love to have the option to include a title or not. My theme pretty much forces me to use one (or can I customize that with CSS too?)