Just a few thoughts from someone who clicks around the site a fair bit...
1) MyThreads has a maximum limit for what it displays, based on age, and I don't get any option to go to the "next page" of "My Threads." I would like to be able to do that so I can see all threads I've looked at. They should die eventually of course, but since a lot of threads get posted every day, you can lose threads from the list quite quickly if you click around the site a lot.
2) When I post a comment, I don't always want to go look at what I posted (I just wrote it after all.) However I might like to go back to the forum I was in before I clicked on the thread I just posted to. A link back to that would be nice. Otherwise I have to go back to Discussions along the top and then back to the forum. That's twice as many hits on your site and one too many click for a lazy web browser such as myself. ;-)
3) Since I always tend to browse using the same machine, it would be good if you could "remember me" in the same way as Yahoo mail or hotmail. I don't mind being asked for my password once a day or so, but it would be nice if I could be remembered between browser crashes in the mean time.
For instance, if I login to Yahoo mail in the morning, it remembers who I am and only asks for my password. When (not if) my browser crashes, I can restart it and get straight back in, no password prompt. I only get asked again every 8 hours or so, which is fine. Something like that on this site would be great, since it's the only other site I look at as much as Yahoo mail! :-) After all, it's just persistent cookies with the maximum age set isn't it? :-)
Just a few thoughts...
Basically though, I love the site, lots to learn from a lot of very clever people who are willing to give their time to help others.