You can make the solution even more concise if you name the combo boxes similarly, like combo1, combo2, etc....
Sub CombineComboBoxes()
Dim x as Integer
Dim str as String
For x = 1 to 8
str=str & Me("combo" & x)
Next x
Me.textbox=str
End Sub
The code seemed to run fine also even if one of the combo boxes had a null value. OK, perhaps that really wasn't more concise!