If you want to run an application, just hit Alt + F2 and then type the name of the program. If it needs to run with root privileges, just type gksu beforehand. For example, to run GNOME Terminal, you would type terminal.
To run Gedit, type gedit. If the program is command line, check the Run In Terminal box (use the Tab key to move from field to field in the dialog box and hit the Space to select a field). This will then open a terminal window and run the command, but be aware that the terminal window will then close as soon as the command has ﬁnished, so you won’t be able to inspect the output.
Want to browse to a file system location, but too lazy to grab the mouse and click the Places menu? Hit the forward slash (/), and then type the path into the dialog box that appears.
Want to rename a file but don’t want to use the mouse? Just ensure the file is highlighted (use the cursor keys to highlight it if necessary) and hit F2. Then type the new filename.
To change the file extension too (which isn’t highlighted for deletion by default), just hit Ctrl + a and then type the complete new filename.