I've been a big fan of Part-Time Investor's PAAY calc. You can find his article on how he uses PAAY here. If you have not read it, it's a pretty interesting metric to aid in determining a companies current under/over valuation by looking at its current dividend rate against its dividend rate over the past year.
*** Edit ***
After the comments by PTI I went and created a new version which is quite a bit more accurate. I've included the original PAAY calc results in the comments below. They were very wrong in a couple cases. The new spreadsheet can be found here. Again, it's not perfect but it is much closer. I used (O) as an example in the new version because it changes its dividend payout much more frequently. I averaged the div payout into two 6 month blocks in (O)'s case. The new version returns these results:
(F) +19.46%
(O) -2.63%
(RCI) +15.36%
(TMP) +0.34%
(WEC) -9.38%
(WMT) -1.26%
*** End Edit ***
Save a copy for yourself and modify the cells in bright blue and the rest should take care of itself.
Unfortunately GoogleFinance only offers up dividend information on Mutual Funds. (I'm not complaining though because what they offer for free is fantastic!)
As always, if anyone has suggestions or improvements to make they are more than welcome.
Thanks,
~Zalach
Disclosure: I am long F, WEC, TMP, WMT, RCI, O.