I use the following shortcuts all the time in Excel:
CTRL-UP, CTRL-DOWN, CTRL-LEFT, CTRL-RIGHT - These move the view to the beginning end, left, right of a block of data. Or if a blank cell is selected, they move the view to the closest data filled cell in the indicated direction. This is incredibly useful for moving around large spreadsheets.
CTRL-SHIFT-UP, CTRL-SHIFT-DOWN, CTRL-SHIFT-LEFT, CTRL-SHIFT-RIGHT - These do the same thing, but also select all the cells along the way. Much more efficient than using the mouse for selecting long lists of data, or deleting large areas of empty cells
These shortcuts, as well as their Mac equivalents (CMD instead of CTRL), do nothing in Numbers 09. I'm going to send this post to Apple as feedback as well. Get on it Apple!
I work with spreadsheets from several hundred to 70,000 lines long, and currently use VMWare Fusion to run Windows Excel 2007. Excel 2008 for Mac is not an option because it is horrendously slow comparatively even though it doesn't have to run through a virtual machine. If Numbers could be a Mac-native Excel replacement for me, I wouldn't have to run Windows at all (Woohoo!). Unfortunately there are too many details like this missing. Hopefully in a few years!