My MacBook is getting too hot.

Open activity monitor, sort by cpu, what is running near the top?

Here's a detailed explanation of how to use Activity Monitor to see what's causing your machine to run hot:

http://support.apple.com/kb/TS1473?viewlocale=en_US&locale=en_US

Anything that's heavily loading your CPU and/or GPU will not only drain the battery quickly but will also generate an unusual amount of heat.

No, your desk is not the cause of the heat. What did Activity Monitor tell you?

Are you sure you selected All Processes in Activity Monitor's drop-down menu? If you don't do that, you won't see everything that's runniing, and you may miss something that's using a lot of CPU cycles.

If you're sure you selected All Processes, and the CPU temperature was still above 80-90°C, you should run the Apple Hardware Test and see what it reports.

Your battery is always cooler than most other parts of the machine, because it is isolated from the major heat-producing components.

Before running the Hardware Test, try resetting the SMC and see whether that alone produces any change:

http://support.apple.com/kb/HT3964

If not, run the Hardware Test:

http://support.apple.com/kb/ht1509

Probably is. If your running a flash intensive website flash can take over processing power. If you dont care about the flash then you can hit CMD+ALT+ESC and find the flash that is using so much and force quit it. Mine gets really hot when I rip a dvd, its pulls nearly 180% usage for almost an hour. I bet thats whats causing it.

Talking about Flash, make sure you have the latest version, cause older releases may be vulnerable to attacks which in turn could manifest themselves as a severe CPU overload.

As for the work surface, could help to raise the Mac a bit off the desktop to let air circulate better underneath. I use a Roadtools Coolpad, totally passive, but there are fancier pads that have cooling fans included.

Flash is a horrendous energy and processor hog. With so many websites loaded down with Flash content (much of it just advertising), it can be hard to avoid having Flash gobble up resources, run down your battery and drive your MBP's temperatures way up. Things you can do are:

- Close browser windows and tabs you aren't actively using. An open window or tab that has Flash content in it is gobbling resources even when it isn't the active window or tab.

- If you usually use Safari for web browsing, install ClicktoFlash, which prevents any Flash content from running until you click to authorize it:

http://clicktoflash.com/

I don't know whether there are similar plug-ins for other browsers.