There's no such thing as "the repository". There can be n repositories. All of them can be browsed either by pointing the web browser directly to the repository or by other means.

Let's see...

The Extras repository maintained by the community is what you see when you go to downloads here.

Other repositories are visible here:
http://maemo.org/packages/repository/
Especially Extras-devel and Extras-testing are interesting for those looking for software. It's just that apps from there may burn your battery, break your screen and kill your speakers.

Another source is the downloads.maemo.nokia.com repo, which you can browse at the "Ovi Store" section of Maemo Select.