10 Navigation Reminders

1. Arrow Keys - Moves one cell in each direction
2. Ctrl + Arrow Keys - Moves to the edge of current data.
3. Shift + Arrow Keys - Extends the selection by one cell
4. Ctrl + Shift + Arrow Key - Extends selection to the last nonblank cell in a column or row
5. Delete - Deletes the contents of selected Cells
6. Alt + Enter - Starts a new line in the same cell
7. Ctrl + Spacebar - Selects the entire column of current selection
8. Shift + Spacebar - Selections the entire row of the current selection 
9. Ctrl + Pageup - Goto Previous Worksheet
10. Ctrl + Pagedown - Goto Next Worksheet

Do you have a mouse with programmable buttons?

Make your Mouse Wheel Push left Ctrl + Page Up
and your Mouse Wheel push right Ctrl + Page Down

When you do this you can cycle through worksheets in Excel very quickly.
This also works with most programs that have a tabs for navigation.