1) Youtube video download--> It adds a button on the youtube's videos, just click on them and download

YouTube Video Download for Greasemonkey

2) Google cache continue redux --> When an interesting website has been removed it is pretty useful, here is the description:

Add links to Google cache results to allow continuing using the cache, keeping search terms highlighted

When viewing a page in Google's cache (e.g. Google cache of userscripts.org), this adds yellow "cache" links next to each page link. Clicking the yellow cache link opens the Google cache version of the associated page link, allowing the user to continue browsing the site through Google's cache.
http://userscripts.org/scripts/show/30878