This depends a lot on where the EGT probe is mounted, as pre-turbo EGTs are always higher than post-turbo EGTs. It also varies somewhat from car to car.
In the past, HKS has recommended that downpipe installations not exceed 1380 degF, and pre-turbo (exhaust manifold) installations not exceed 1550 degF.
For more information, see Brad Baur's EGT Gauge Installation FAQ and Tom Stangl's Westech EGT Install FAQ. According to Tom, 1650 degF (900 degC) is the ideal point at which to finish a 1/4 mile run.
Do yourself a favor and get a datalogger. EGTs are nice, but they're not the be-all of engine monitoring - not by a long shot.