"T. Valko" wrote...
....
B2 [Topmost result cell]:
=A2

That assumes A2 is not an empty cell. Might be better to use a "lookup"
formula to get the first entry of the range.
....

Fair point. It should be

B2 [array formula]:
=VLOOKUP("?*",A2:A20,1,0)

if col A contains only text, or

=INDEX(A2:A20,MATCH(0,-ISBLANK(A2:A20),0))

if col A could contain anything.

In B3 normally entered:

=IF(ROWS($1:2)<=SUMPRODUCT((A$2:A$20<"")/COUNTIF(A$2:A$20,A$2:A$20&"")),
INDEX(A$2:A$20,MATCH(0,INDEX((A$2:A$20<"")
-ISNA(MATCH(A$2:A$20,B$2:B2,0)),,0),0)),"")

It'll be slower. The COUNTIF call goes through the full col A range aginst
itself in each formula, while my formula only goes through col A against the
previous cells in col B in each formula. Also, the extra INDEX call needed
to avoid array entry wouldn't help recalc speed.

On a side note: . . .

Works in Excel 2003. IIRC, this was something MSFT documented as fixed in
XL2003. Your diagnosis is correct. So upgrade already.