One of the great things about blogging is that you get to share links to your friends and to all your favorite places online. By default, all of these links get thrown together in the Blogroll, but if your blogroll is getting too long, you can split it up into different categories. For instance, I have one links category for My Students, one for Useful Websites, one for the Student Blogging Challenge, etc.
Using the Links Widget
Once you have your link categories set up, you can make a Links Widget for each category. Put them in your sidebar and move them around wherever you like.
Do remember, however, the sidebar is for your reader. Keep the links widgets lower than your subscription, search, posts, and categories widgets. But usually, the links widgets go higher than just-plain-fun widgets like blog badges or a flag counter.