Couldn't find a good place to post this, so I'll try here. Feel free to move it. I didn't figure it belonged in the WordPress idea section, since that seems for the software only.
Anyway, I have the following suggestions, since it is a pain trying to get around the plugin section:
#1 - Saving as favorites.
#2 - To extend #1, custom or multiple favorite types. Like you could allow us to make our own or just provide more than one. Mine, for example, would be Using, Not Using, and Watching. Then anything that doesn't fall under those 3 would be assumed brand new (Since W.org has the tendency to string out all the new plugins all throughout its lists.). I like to go through all plugins by hand, so this prevents me from spending a week making a by hand list.
#3 - Corrected lists. I am sick of seeing projects pop up all over. Either they should be added from the second they touch the site, even if they have nothing to offer, or they should be added on the date things fall into place and it is officially launched. Right now, projects can suddenly appears days back in the new project list. Now I am using this list as a static list to make sure I cover all plugins available, but since it can update randomly, I have to keep going over a lot of the pages to see what I missed. Projects should not appear randomly throughout.
#4 - Allow commercial projects and get the rest of the unlisted ones on the site. I'm against commercial most of the time, but... I don't like having to go all over just to find what is available for WordPress. I have used Joomla! some in the past and they are an example of a site that has everything available for extensions (I think) listed, even if commercial. I don't like having to go to other sites to find updates or new extensions.
#5 - A small, quick to go through, alphabetized list of modules would be great. See the Drupal module list on their page. You click name, you can then filter by version (Not saying I want this on WordPress), and then you get every extension that works for that version, all displayed on the same page, with a teaser type look. WordPress, with so many plugins, could make it a one liner and extremely compressed. Drupal actually has about the same amount, overall, and they put it all on one page. You can even hit the page with something like flashgot and download the latest versions of each module with one click. Great for testing.
#6 - Categorization. Tags are nice, but then look at the Joomla! extension page. It is all categories and they are all placed into one. It is better than scouring each tag, hoping you made the right choice for a tag selection and hoping that each plugin that should be under the tag, actually is. Think about the projects that fall under a major category, but have such random tags because they are the only thing that does something.
#7 - User voteable works or doesn't work for latest WordPress version system. Ok, let me give you an example. People stumble upon an plugin, it then asks that person, after a download, if it works on version 2.51 for them. If they say yes, then it lists itself as compatible, if no then it doesn't. Enough yes over no and it is fully listed and shows up as compatible (Usable by hopefully future upgrades to plugins). This would also be very helpful to people going to the page. The voting gets reset with every new version uploaded or can be saved on the version page next to a version.
Just some thoughts for now, I certainly don't think all should be implemented. Just some would be nice. The plugins page isn't that easy to use.