I want to enter a formula that will reference a particular cell, and then
allow me to drag the formula down so it references every third cell.

So, if my data is:
A
1 XOM
2 WFT
3 SLB
4 HD
5 LOW
6 BAC
7 GE
8 MSFT

(Imagine the list is much longer) and I would like to write a formula that
allows me to create a smaller list composed of every third entry. So the
first entry would be XOM, then when I dragged the formula down, the next cell
would be HD, then GE, and so forth. Any ideas?