Not really much unique content today... but if you're a java person here are a couple very helpful links. I've often tried to figure out exactly which gc algorithms are being used, how that corresponds to which jvm params you use, and if certain young/tenured garbage collectors have to be used together. I've known for a long time that jconsole will show you which ones are being used, but the names it uses don't always seems to correlate to other documentation, jvm params, etc.
So I got on this hunt the other day of figuring out the specifics and found these two resources which in my mind, spell out all the details!
A Sun engineer's blog post
Neo4j tuning information - see the table a couple paragraphs down from the section title.