The >only< sleep hack that seems to work (and I've tried many) is the 15-20 + coffee nap. You know how it is: you wake up, and for the next few hours tons and tons of distractions present themselves (and I don't mean trivial stuff like Twitter or emails and such). Eight hours or so pass, and you've only managed to deal with tedious administrative stuff or other non-critical work that won't count in the long run. By that time you're usually dead tired - so the trick I use is to have a normal-sized coffee really quickly, then nap for 15-20 minutes or so (not much less and certainly not much more). The effect of the coffee kicks in right when the effect of the extra sleep kicks in, and if you don't sleep too long you won't get the usual 'exhaustion' that comes from lengthy sleep.
This trick has worked for me every single time (except when I was severely sleep deprived). It may not feel productive to have a nap when you should be working - and obviously it's not possible for everyone to do this - but I've personally found the extra energy and focus that you get invaluable.
[1] "Sleepfaring" by Prof Jim Horne: http://www.amazon.com/Sleepfaring-Journey-through-Science-Sl...
http://www.amazon.com/Sleepfaring-Journey-through-Science-Sl...
Reading it can put you to sleep, but there's interesting stuff there. Some highlights, off the top of my head:
1) 'Coffee naps' are effective - i.e. if you're really tired and have to stay awake, drink a coffee quickly and nap for 15 minutes or so.
2) If you are sleep deprived, you only have to make up a fraction (I think it was something like 1/4) of the lost sleep - not the entire amount. It's easy to sleep too much.
3) If you can't sleep, instead of tossing and turning it might be better to simply get up and do a boring routine activity (e.g. puzzles), until you get tired again.
YMMV etc. - sleep is still not that well understood.