When browsing technical sub-forums, I noticed that there are a few threads which end with the OP replying "Thanks, it's solved/working now!" or something to that effect and are still not marked solved. Similar is the case with one-shot-posters who post a query which is duly answered but never return (or return just to read the answer) to make a reply or mark the thread as solved.
This has the consequence of valid solved threads not contributing to the total "solved thread count" of the sub-forum and the forum in general and more importantly denying +1 solved count to all the members who contributed to the discussion. The problem is that there is no way a thread contributor, who is pretty sure he has answered the OP's question, can mark the thread as solved.
So here is the deal: in case you encounter a thread which you are pretty sure should be marked solved, you can "report" any post of the thread (preferably the first one) with a comment along the lines of "IMO should be marked as solved". Also, please don't shy from reporting threads for which you are the only contributor. ;-)
I can't guarantee the "resolution" of each and every reported post given that moderators have limited time but this at least seems like a step in the right direction.
Ask away if things are still unclear or in case you disagree with something!