Profile with a 'euro bb' for a great bmx crank for that fixie, its the bmx industry standard and if you think you can break it, there's a beefier version!!!
Shimano DX cogs are worth their weight in gold for cheap single speed build ups.
Diacomp 990 brakes are the standard for bmx as well.
S&M platform pedals, lifetime warranty, you break them or somewhat damage them they'll replace them, no bones about it!!!
One last thing, there are some BEEFY bmx chains out there, some could probably be run on a motorcycle, something for single speed and fixed off roaders to consider if the local single track has alot of logs that seem to eat up chainrings and chains!!!