I haven't been using Weasyl much because, frankly, I'm not really big on the User Interface (UI). I'm kind of just leaking my brain on pixels, I'm sorry it'll most likely read as a confusing pile of disjointed thoughts.
!!!!WARNING: I'm about to have an opinion on the internet!!!!
Improvements I'd personally like to see:

• Comment Previews in the message center such as DeviantArt's set up would be really handy. The current message center feels clunky for answering comments, especially if you get a lot of them.
• Please move the "Remove All" button.
• Please move it.
• I'd like to see Folders act more like folders, and less like personal categories in your gallery. Unless I'm missing the option, from what I can see, there doesn't seem to be a way to remove an image from your Main Gallery. I'd like the ability to hide stash stuff in scraps. ;) I'm an organization freak, I want to move and shift my gallery around.
• I hate to admit it, but I miss the Recent Watchers message set-up Furaffinity has. I'm very picture oriented, I like seeing the person's username and icon in my message center when they watch me.
• I'd really like profile pages to feel less disjointed. I understand that Weasyl doesn't want to become a carbon copy or every other art site out there and while I respect that endeavor, there are some downsides to reinventing the wheel. Many sites have similar profile set-ups because, well, they work. People dig familiarity. I've made my profile suggestions into a smaller bullet list for some semblance of organization. +Issue: Right now the only way to have favourites displayed on your front page, is a toggle bar located right below your personal gallery bar. I'd like to have my favourites displayed, but not in such a way that in distracts from my personal gallery, after all I want folks to visit my profile and browse my art. It's fairly easy to confuse someone's favourites with their gallery (I've done this a few times, myself). +Suggested Correction: Place the favourites gallery elsewhere on the profile page. Maybe even add the option to organize your profile like Y!Gallery or DeviantArt. +Issue: The entire right hand side of the profile is a clutter. It appears to be one big wall of text and becomes a strain to look at. +Suggestion Correction: Add boxes (I dare say something akin to Tables) to the sections. Maybe repeat between two subtle changes in colour between every other one (Muted Blue/Muted Green/Muted Blue/Muted Green/Etc). Again, Maybe add the option to organize your profile like Y!Gallery or DeviantArt.

That's my current thoughts on some UI tweaks. Of course, my word isn't any better than anyone else's, but I thought I'd share my ideas anyways. i'd love to see Weasyl get more traffic, and some UI updates just might help!

You can check out and follow me on tumblr, I update there far more frequently. Both blogs are for art only, so there's no need to worry about reblogs or non-art spam. :)
http://mottenfest.tumblr.com/ -- CLEAN ART ONLY
http://i-can-smell-cakes.tumblr.com/ --NSFW ART ONLY