Mocha VNC Lite allows your iPhone or iPod touch to connect to your Mac or PC via VNC. For those of you who don't know, VNC is a protocol that allows you to screenshare/control other computers via a VNC client (which is what Mocha VNC Lite is). It is amazing to see this working right on my iPhone. I remember back when I used a Palm device to do this sort of thing and it was very kludgy, but this seems to work rather smoothly.
When you are connected to the computer via VNC, you are able to control pretty much everything on the screen, with the exception of special keys (i.e. command, option, F keys, etc.). You can, however, "pinch" the iPhone's screen to zoom in or out the viewing area.
Now for the gripes. Mocha VNC Lite uses left-clicks on the screen (which can be quite annoying after a few minutes use). You are also unable to change the refresh rate (however, if you click the "+" button, you're given a "refresh option.")
Mocha VNC also offers a paid version which gives you more useful features like extra PC keys, cursor keys, text macros, and a right mouse key. However, the lite version will give most users everything they need for casual VNC management.
You can download Mocha VNC Lite from the App Store for free. At the time of this writing the paid version has not yet been placed on the App Store. Feel free to look at our gallery of screenshots before you download.