Function myname(rng)
Set nms = ActiveWorkbook.Names
myname = "BLANK"
For r = 1 To nms.Count
If rng = nms(r).RefersToRange.Address Then
myname = nms(r).Name
End If
Next
End Function

I have already got this UDF from Bernard Liengme (thank you). It will show
the user defined name of a cell. The problem is that you have to include the
""-signs and a absolute addresss when you use this UDF, like:

=MYNAME("$A$11") will return ABC if ABC is the defined name of cell A11.

The problem is that the "<absolute address" in the MYNAME-function, is not
supported by Excel's AutoFill-function which is very important for me. I'm
not able to program this myself, but perhaps anybody here could modify this
code so that you don't have to include the ""-notation and the absolute
address: =MYNAME(A11) instead of =MYNAME("$A$11").

Please help!