oops. still haven't learnt. I used to work for a global consulting firm and we would have teleconferences at the strangest of hours. i used to always get the other time zones worng back then also.. DOH!
What about? In Data Validation use Allow: 'List'|Source: 0,1
That way you still give the user the opportunity to type a 0 or 1 in the cell but you give them the additional option of choosing from the drop-down list.
Mind you, neither this nor babycody's suggestion address your question of 'Is there a better or other method than data validation?' I don't think there is a better answer - Data Validation does it simply and well.
would a little double-click be nice ? or rightclick ?
Private Sub Worksheet_BeforeRightClick(ByVal Target As Range, Cancel As Boolean)
'Erik Van Geit
Dim Arr As Variant
Dim k As Integer
Arr = Array(0, 1)
Cancel = True
On Error Resume Next
k = Application.Match(Target.Value, Arr, 0)
On Error GoTo 0
Target.Value = Arr(IIf(k - 1 = UBound(Arr), 0, k))