How do I reduce the desktop icon size in Windows 7?

Solution 1:

If you click a blank bit of the desktop, hold down the Ctrl key and scroll down using the mouse wheel, you can scale down the desktop icons until they're almost non-existent.

Ctrl + scroll wheel works to zoom in most applications (browser, MS Office, Windows Explorer, etc.).

Solution 2:

Right click the desktop > View > Small Icons (Classic on Vista). That is the smallest icon size you can have.

If these sizes are still not small (or big) enough for you, then you can hold down Ctrl whilst scrolling the Scroll Wheel to change it to the exact size you want.

Solution 3:

I haven't tested this but I would've thought this was a registry setting, according to google it is :)

[HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics]
"Shell Icon Size"="36"

The value '36' is the default (medium size) if I'm correct, a smaller value means smaller icons.

Note: Fiddling with the registry can be dangerous so only use this if the default 'small/medium/large/extra large' don't suffice.