This is really posted to remind me how to use the Thumbnailer and LightBox extensions now that René Kuss's website has vanished :(

Add the commands in the src attribute and hit save after you have uploaded an image.

Example :

[thumb:height=150,link=lightbox]

<img src="/image.axd?picture=2009%2f4%2fzembian-error-google-chrome1.jpg[thumb:height=150,link=lightbox]" alt="" />

See the post here to see this in action.