Other than making it a sticky, what if you had years of content but like 100+ top threads that has a ton of useful information in them? What do you do with them because once its not a sticky anymore it gets lost in the bunch...
If you have that much content it's perhaps better to put it on a website instead of the forums. What we did is create a sub-forum where members can't create new threads, and put interesting threads there.
I do nothing with them... because what's hot today, or this week, isn't tomorrow, or the following week. I have auto link working, so if anything is just that awesome, then I will hook it into the auto link feature and make it easily accessible via keyword links.
I admit many of those topics are dead, although it's not clear if they would've died anyway, some topics stay alive. Another thing @surfsup can do is create a single sticky thread in each forum, containing links to interesting/best threads of that forum.
We use XenTag for this. This makes the best content easier to find, adds significant pagerank to old threads, and helps categorize the threads as well. It also creates a very organic way for members to discover the best threads.
For example, in addition to your other tags on the thread, you could have a tag for "most liked threads," "most viewed threads in 2014," etc. The more tags you add, the more PageRank will be brought to the threads and the more helpful links will be added for people browsing for content.