How about a little cheating?
Format the range (whole column??) with a wingdings font.
Then format|Cells|Number tab|Custom
type alt-0252 ; alt-0252 ; alt-0252 ; alt-0252
(Hold down the alt and use the number keys from the numeric keypad--not above
QWERTY)
It should look something like:
ü;ü;ü;ü
(u with umlauts)
Anything you type will be formatted to show a checkmark.
There are other checkmarks available, too.
Take a look at Windows Start button|Run|charmap
Pick out the one you like and notice the keystroke combination in the lower
right corner.
If you want to check to see if that cell has been checked, you can:
=if(a1="","Nope","Yep")
(since anything will cause the checkmark to appear.)
If you wanted to count them up, you could do:
=COUNTIF(A1:A99,"*")
or
=COUNTIF(A1:A99,"<>")