I currently use Google Code to host two open source Eclipse plug-in projects: Eclipse XPS and Eclipse Printers. Google Code is pretty cool. It provides a Subversion server, a wiki, download pages and an issue tracker for your project. All these functions are available through a basic - yet usable - web interface.
Unfortunately, the download pages are a little bit too basic. There is no way to set up an Eclipse update site. An Eclipse update site requires a specific directory structure but Google code does not allow the creation of subdirectories in its download area.
This means that people can not use Eclipse's built-in update manager to install your code. And more importantly, they can not use it to stay up-to-date and install the latest fixes.
Of course you could commit your update site to subversion but that really defeats the whole purpose of having a download section where each download is counted.