If you’re a fan of Firefox (mainly because it’s an awesome tool for webdevelopment) like me. You should already know that there’s an additional console for developers (I’ve did not until five minutes ago). When you press Shift + F2 it shows little input bar on the bottom of the window. For example type the following command :
screenshot --clipboard --fullpage
Press Enter and BANG! Screenshot of a entire page in your MEMORY!
Mother of God… This is so awesome!
PS. Try different commands, you can use Tab for completion and help to list them all.