yes, http://browsershots.org/ is the website which allows you to capture SS (Screen Shot) on different browser on different OS.. Its slow but useful when you don't have resources at the same time..
If IE browser you have IE Tester .. which have all IE versions in one..
Other than this I don't know.. If you found it then please let me know
I would classify this question into 2 parts -
1. Browser compatibility testing -> Verification of User Interface
2. Browser compatibility testing -> Functionality verification on different browsers
1. For user interface, you can either use online available tools as mentioned by Zahid and Kunal. You can search the net for all available tools.
We do not use any tools but actually do a manual verification on different browsers. This is more reliable method.
2. Functionality verification on different browsers. We are currently using Test Complete automation tool.
This tool supports IE, Firefox and browsers based on webbrowser control.