As someone who has been teaching audacity to college students and k-12 teachers for several years, I've noticed a couple of strong usability flaws:

1) When the pause button is selected, most of the editing options are greyed out. As a result, users think that the program has frozen when in reality all they need to do is press stop instead of pause.
2) Users are often confused by the fact that the .aup file requires the "data folder" to work (since this violates their mental model for how "saving a project" should work). Even when I emphasize to users the importance of keep the .aup file and the data folder together, I still always have one or two who manage to move the .aup file (to another computer, to another place on their machine) without moving the data folder).
3) Most users want to export files to mp3 and the additional step of using lamelib is cumbersome to explain and implement. (I recognize their might be legal reasons why audacity doesn't export mp3, but I figure it's still worth mentioning).

Anyway, I certainly can post these suggestions to the audacity website myself, but it would be great if a group such as OSAAC could report suggestions such as these that were endorsed by a body of teachers who had expertise in usability (and experience teaching audacity to students).

I also think it would be cool to have students conduct usability tests of audacity and report the results to the development community. Indeed, I'm thinking of doing a project like this for my advanced "user testing and documentation" course next spring.

So, anyone have any other suggestions about improving the usability of audacity (or any thoughts on my suggestions)? Anyone have any advice to share about having students do usability research about open source software?