http://en.wikipedia.org/wiki/Hexadecimal_time
I like the idea of the 16-hour day, the 256-minute hour, and the 16-second minute. It makes at least as much sense as the divisions we have now; more in certain circumstances.
It's sad to see the gregorian calendar madness from over 400 years ago will probably even be carried into the space-age.
For example, an intercalation scheme that intercalates single days and is based on the mean Martian tropical year of 668.5921 days can be approximated closely with a cycle of 45 leap years in 76 years because 66845⁄76 ≈ 668.592105 and 0.5921 × 76 = 44.9996.
Easy, huh?
Well, here's more: http://en.wikipedia.org/wiki/Timekeeping_on_Mars