These suggestins are mostly usability-related. I haven't used the forum for very long, but these are things that immediately popped-out at me.
Search When searching the forum using the forum-wide search box, it seems weird to be redirected to the search page first. Not a showstopper obviously but a little odd in terms of user experience. The first few times it happened I thought I may have done something wrong.
Post-Post Screen After making a post, the 'intermediate' page with the "message posted successfully' always appears. I'm not sure if this page is simply to tide the user over while the database is updated, but I think the following changes would be worthwhile.
1. Provide a user-level setting where a user can configure their 'post-post' preference (i.e. after I post I always want to go 'back go the thread'). After selecting this preference, the user would not have to go through the intermediate page, thus saving time. Even if the intermediate page is required, allowing the user to select their preference would be a nice feature.
2. The first option in the 'intermediate' page, 'go back to message', is a bit confusing. My first thought was that this would take me back to the 'compose message' page where I created the post. A more appropriate wording could be 'go back to thread'. In reality, I don't even think the first option is required since redirecting back to the thread is the default behavior.
3. At worst, I think a message should be shown on the 'intermediate' screen which says... "You will be redirected back to the previous thread in x seconds....".
Attach I definitely think there needs to be a more prominent 'attach' button. I like having the attach feature in the message composer, but I think a button below the composer would also be nice since that is where it is located in most forums. I've had numerous people wonder why the 'attach' feature isn't available, when it is.
Prominant Post I think the 'Post' button should be located closer to the bottom of the message composer in 'advanced' mode. When I complete a post, I'm usually ready to immediately submit it, but I always have to scroll further down the page to click the 'Post Message' button. Maybe additional 'Post', 'Preview', 'Cancel' buttons could be added right below the message composer, in addition to the existing buttons at the bottom of the page.
Mouse Hover Behavior This is one of the biggest usability enhancements I'd like to see made. In the dynamic-flyout menus ('Reply', 'User Control Panel', 'Admin Control Panel', 'Subscribe to this forum'), it is very difficult to tell what is clickable and what isn't. IMO, any option that is clickable should have its hover style for the cursor changed to 'pointer' (the hand).
Example:
For the 'Subscribe to this forum' button, which shows an arrow when you hover, clicking on the button causes nothing to happen.
For the 'User Control Panel' button, which shows an arrow when you hover, clicking on the button takes you to the 'EditProfie' page.
Both of the above options are presented to the user identically, but the function differently. IMO, the 'User Control Panel' button should use a 'pointer' css hover to indicate that it is clickable.
SEO I'd like the ability to integrate category names in to the url for SEO purposes. In my forum I plan on having categories for different sports (football, basketball, etc) and it would be nice for the search engines to easily recognize what sport each post references.
Theme I'd like to see one of the default themes use a logo with a hyperlink that is click-able since this is very common for websites.
Preview Window
I think there should be a 'Post' button while in Preview mode, rather than forcing the user to cancel-out and return back to the message (less work is better).
Hyperlinks When configuring a hyperlink in a message, I see a couple of problems.
1. If you highlight some text, then click the 'hyperlink' button in the message composer, the 'Title' is not pre-populated with text that was highlighted. This is confusing because I don't know if I have to re-enter the Title, even though I already highlighted it.
2. I think a target should be selected by default, specifically 'open link in new window', since people rarely want users to navigate away from their own site. Getting rid of the default 'not-set' option altogether and setting one by default means that (at worst) 50% of the time the user doesn't have to configure this option, improving usability.
Editing Own Posts When looking at a thread where I have made my own posts, the default button in my own posts should be 'Edit Message', not 'Reply to Message'. I would rarely want to reply to my own messages, so it seems like 'Edit Message' would be more easily accessible it if was shown by default. When I first started using my forum, I had a hard time figuring out how to edit my own messages because this option is hidden under the 'Reply to Message' button, which isn't intuitive at all.
That's all for now.