Up until now, the only way to access the Android Market was directly via your mobile device. That has all changed with the official launch of the Android Market on the web.
The new web interface gives you a simple and easy to use way to score new apps for your phone. Search apps, find stuff you like, and after signing into your Google account you can tell the site to download straight to your phone without even having to plug it in. I downloaded an app via the Market on the web and it began downloading on my HTC Desire nearly instantly after clicking the download button. Check out the Android Market in its full PC glory