In the Stocks Dashboard Widget, the up- and down-arrow keys will change the selected stock, and the left- and right-arrow keys will toggle through the different time intervals (1d, 1w, 1m, etc.). This may have been possible in earlier versions of OS X but I have only noticed it in Mountain Lion.
[kirkmc adds: Not a game-changing hint, for sure, but if you use the Stocks widget regularly, it can save time.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20130118151446230