If you're interested in website design you may already regularly go to the View menu in Firefox and select 'Page Source' to see the source code for certain pages. This is a handy feature, but is already common to most browsers. However Firefox takes this nifty feature one step further. Select only a portion of a web page by holding down the left mouse button at the start of your selection, then dragging the cursor to the end of your selection and releasing the left mouse button. Now right-click on this highlighted selection, and in the context menu select 'View Selection Source'. The source window will open and only show the coding related to the portion of the web page you've highlighted. This is very useful if you don't want to wade through large chunks of code just to see how a neat effect works on a page, or if you can't figure out which portion of code relates to which section.