I found this command today when I was looking for a way to download a bunch of files from a web page quickly. Basically this will go to every link and download it. It will follow links 1 layer. More details on it here.
wget -r -l1 -H -t1 <url>
So for instance you can run that on a page of your favorite tumblr and get all the images and text posted. That I used it twice after just learning it (once for the files download, again for images download) makes it feel quite powerful.
