Matt wrote...
I think my issue is best displayed with an example:

Here's my rows of data:

Column A
Bob
Dave
Dave
Eric
Simon
Simon
Simon
Simon
Tom
etc....
....

I'll assume this is in Sheet1!A1:A10000.

Is there a formula that can return the following:
Bob
Dave
Eric
Simon
Tom
etc...
....

Enter the following formulas in Sheet2.

A1:
=Sheet1!A1

A2 [array formula]:
=IF(SUMPRODUCT(COUNTIF(A$1:A1,Sheet1!A$1:A$10000))
<COUNTA(Sheet1!A$1:A$10000),INDEX(Sheet1!A$1:A$100 00,MATCH(0,
COUNTIF(A$1:A1,Sheet1!A$1:A$10000),0)),"")

Select A2 and fill down as needed, worst case into Sheet2!A3:A10000.