New Drupal modules
Also at Drupal.org of course, and to be specific, at this address:
New modules are published daily, so the RSS feed is a great way to keep an eye on interesting development.
As an alternative you might find this list at Drupalmodules also interesting:
Drupalmodules.com has great potential to provide a better service in searching for the right module but it's not quite there yet. Each module can be rated for features, reliability, ease of use and documentation. In addition you get a list of related modules and user reviews. Many modules however, don't have any ratings avalaible however. Or there are too few available to get a reliable picture.
Quality control and module activity?
Also it would be great if the rating system would be expanded with a bar like 'code quality' and a selected group of accomplished programmers would be able to rate modules for their quality of code. (efficiency, system load, number of queries etc.etc.)
And maybe a quick visual indication about the development activity. Is somebody working on a new version of a module? A very common question in the issue queue for a module which has been around a while without updates.