This is a really hard thing to do a search on, so I'm posting it here
to hopefully be enlightened.

1) What does the double dash "--" do in a function?
2) Specifically, what does it do in this function:
=OFFSET(Y!$B$2,,,SUMPRODUCT(--(Y!$B$2:$B$2000<"")))

3) Final and related question, I want to have a drop down menu where
the options change based on the field to the left of the menu.
Date Name Account #
7/26/06 Joe 123456
7/26/06 Dan 654321
7/30/06 Joe 987654

I would like to have the account number pull from a long list of
account numbers like this...
Joe 123456
Joe 987654
Dan 654321
Dan 456789
Joe 555555

and have the drop down menu give me the option...
Row1 7/26/06 Joe (123465 / 987654 / 555555)
Row2 7/26/06 Dan (654321 / 456789)
Row3 7/30/06 Joe (123465 / 987654 / 555555)

so I can select which account number I want to use.

Any ideas?