Yes, something needs to be done!
1. Search2post (it needed a catchy name) - Yes it would be excellent, however I dont think its enough.
2. Sticky the common perpetual threads (those that duplicate every time they fall off the first page). - I think this is the most efficient of all suggestions (best effect from least amount of work). Preferably combined with creating a start post with a brief description and a few comon arguments. This would create a full page of stickies, which is bad, see next idea for a sollution.
3. IS.moderated & IS.public (old usenet idea). Create a new locked subforum IS.moderated, move unique suggestions there, put the unlocked IS as a subforum to this one. - I dont know how much work it would be for the mods, maybe its easy to create an "aprove" button. Variant of this would be to create a subforum IS.trash and move all bad posts there (with a comment on why ofcourse)
4. Lock all spam immediately, with a simple comment like "learn to use search", "learn to put usable subject" etc. - Ive seen this work quite well in similar forums it takes awhile for ppl to learn and TS has a high newb-factor so it might not work at all.
5. Edit the subject immediately when needed, I realy hate those "I got an idea"/"We need this"/"Please devs"/"Scawen!!!!!11oneone" -posts. - I beleve this would be too much work for the mods tough.
6. Rework the "Suggested improvements log" imho it´s useless since it should prevent the current mess and it doesnt, maybe split it up into threads in a subforum (and combine with 2,3 and 5) - This would be alot of initial work, I can volunteer to threadify a coupple of pages if needed.