Site / blog switcher? (or nice way to to link to external pages)

Does anyone know if there is a good site / blog switcher for WPMS networks. I am looking for an attractive and functional way to switch sites.

I have a number of sites around the same topic running on a network.

Something like the Theme Switcher plugin but for sites/blogs instead. It can go at the top in the sidebar or slide out. Just need a nice way to manage links to the other related sites. It can ten be a non WP solution.