- Cache of third party libraries to speed up fetching (it really makes a difference!)
- Releasesof your own software to it is available to the others in the company.
As of today there are three Maven repository managers (see http://docs.codehaus.org/display/MAVENUSER/Maven+Repository+Manager+Feature+Matrix): Archiva, Artifactory and Nexus.
I have made a small evaluation (I have tried them for about 30 min each). I must say that they are all very similar. They will all probably work for you. They are all web based.
My favorite for now is Nexus. This is because the GUI is rather simple, you can create virtual groups of repositories.