Just start typing to get the function you want in Excel 2007 and 2010. A new type-ahead feature is now included for Excel functions.
Example: Start typing =VL and notice that the VLookUp function pops up in the dropdown list. If it’s at the top, press Tab and it will enter the function and open the left parenthesis. If it is not at the top of the list, you can either continue typing until it is, or use your down arrow key to select the function you want, followed by the Tab key to enter it.