To navigate quickly in Excel, hit ctrl and the arrow that points in the direction you would like to go.
This will take you to the last row or column containing continuous data. Hit shift-ctrl and the arrow key of your choice to select data.
Keep hitting ctrl-arrow over and over as needed until you have navigated to the bottom, top, left or right of your spreadsheet. Put the shift (ctrl-shift-arrow) in there to select all the data you want.
Happy Trails! (Get it? Trails, Navigation? Get it??)
