How little I know ;)
Writing about web page http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html
I was having a technical chat with Rob Harrop of Interface21 fame and we got talking about java synchronisation and the farce that is double checked locking, both concepts I thought I had a handle on.
Anyways, I decided to do a bit more reading and am astounded at how much I don't know :) Admittedly I don't feel too bad about this because I have never explicitly looked at these in depth, but here are some interesting links:
I thought I knew quite a bit about java until I spoke to Rob :)