The SB-600 works with every Nikon camera made for the past 40 years. It's the only flash, along with the SB-400 and SB-800, that works properly with the current Nikon digital SLRs like the D50, D40, D80, D200, D2Xs D70, D2H and D2X and their new i-TTL exposure system. Read here about how to use it remotely, which it does for free with the built-in slave.
I prefer the SB-600 over the SB-800.

Power Output
Rated GN 98, feet at ISO 100 at the 35mm setting.
Manual 1 - 1/64 power in third stops. (SB-800 turns down to 1/128 power but has 2/3 stops more power at full)
Exposure Modes
TTL (TTL, i-TTL and D-TTL) and manual with variable power.
No non-TTL "A" mode. This is the mode you'd use with a film camera made before 1979, but since the mode isn't here just use manual for historical cameras.
No idiotic repeating strobe mode. No one ever uses that mode.
Its good that it lacks it because it makes cycling through the modes with the MODE button much faster, since there are none of the trick "sales" modes to bog things down. Sales modes are useless features added to flashes to make the innocent spend more money on them.
Exposure Compensation
You can dial in up to +3 to -3 stops flash exposure compensation on the flash, just press the dedicated + and - buttons. That's more than you usually can dial in on the camera.
Zoom Settings
You can shoot with any lens, however the marked settings are from 24-85mm, and a flip-down panel covers 14mm.
Size
2.7" W x 4.9"' tall x 3.5" deep (SB-800 is 2.8" wide x 5" tall and
3.5" deep)
Weight
13.75 oz. (390g) with 4-AA alkalines, 10.6 oz (300 g) empty.