Any display is compatible with Mac OS X as long as it has a VGA or DVI or HDMI or DisplayPort or Mini DisplayPort input.
You can change the orientation of the external display via System Preferences > Displays.
The Dell U2711 and U2410 displays seem to be popular with Mac users. Both have VGA, DVI, HDMI and DisplayPort inputs, and have powered USB2 hubs. The U2711 uses the same LCD panel as the TBD, but is anti-glare and uses CCFL backlights.