I remembered the day when I had the same question and to get an answer I asked this question at several Android forums. I expected the members to come out with a positive answer, but unfortunately NO.
There is no way to download Android Market applications directly to your PC using the official Android Market site.
If you just want to store Android apps on your PC, here’s how you can do that.
How to Move Android Apps to PC?
In case you wish to store Android apps on your PC, you will have to first download them to your Android device -> Install a backup application ->Backup the apps -> Then transfer them to your PC using Bluetooth or a USB cord.
Or if you want to download Android apps on your PC you can read this.
How to Download Android Apps to PC?
If your device does not have an internet connection or for some reason you are not able to use Android Market on your device i.e. you are unable to download apps on your device, then there’s a “NOT RECOMMENDED” way of downloading apps first to your PC and then moving them to your Android device and install them.
There are innumerable sites that host Android Market applications on their servers. You can download Android apps from these external sources.
I don’t recommend using external download sites as you can never trust them. The apps may or may not be tampered, they may contain viruses or worms and they can even be used to hack into your system and leak personal details.
I have made a small list of sites hosting Android apps on their servers. Have a look,
These sites may not contain all the Android Market apps, but they do have some most popular and useful ones.
I recommend using Android Market to download apps if possible and if not use the above sites. Use the sites at your own risk.