CTRL+U will delete from current cursor position back to the left. This is very handy for when you are keying in a password and you goof up and you don't want to waste time waiting for the error message, etc, etc. Just press CTRL+U, then retype your password correctly. CTRL+U also works at the command prompt, in the web browser address line, and in most other places.
ALT+Fn will switch you from a text console to some other console.
CTRL+ALT+Fn will switch you from the GUI to some other console.
Please make good use of "File Name Completion". Don't go nuts because you can't type correctly. "File Name Completion" is used through the [TAB] key. All you do is start typing a filename and then press [TAB] to complete out that filename. If 2 files are named the same thing, then pressing [TAB][TAB] (pressing TAB twice) will cause the "File Name Completion" to offer you a list of choices that it can't decide between. Once you type some characters to get it past the "stuck" point, you can press [TAB] again to finish completing the filename. This will give you great savings in misspellings and number of keystrokes.