LJ Multi Column Archive is a WordPress plugin/widget that allows you to display your archive list with multiple columns.
I developed this plugin as I wanted to make use of the space I had in the sidebar more effectively, while still keeping the links to all the archives available.
Depending on how old you blog is you can set the Archives to display either a list of Months with Posts, a list of Years with Posts, or a list of Days with posts.
Archive links can be shown with or without post counts.