Kishan Bagaria from deviantART has created a very handful application that allows users to change the start menu icon which is also known as Orb. The application is being distributed by TheWindowsClub as a freeware.

Win7 Original Orb

Original Start ORB

All you need to do is open the application, browse for an ORB and open it. Windows 7 Start Button Changer automatically backs up the original button and you have the option to restore it later whenever you want.

Windows7 Orbs

Sample Orbs

Download Windows 7 Start Button Changer from Here. In the package, you will also find 10 orbs samples. You can get more from deviantART or just by searching on the internet. Personally,my favorite is the  power start orb created by sergiogarcia9 .

PowerStartOrb

Power Start Orb by sergiogarcia9

Please note that on some computers it is essential to run the application as an administrator in order for it to run correctly.