GridDropDown

Private Sub DBGrid1_KeyDown(KeyCode As Integer, _Shift As Integer)
    'This is to display the list when the user presses the down
    'arrow key. This makes it easier to make a selection during
    'data entry. The user doesn't have to go to the mouse to
    'click the button.
    'change the number here to your appropriate column
    If DBGrid1.Col = 2 Then
        'that has the button, other wise you will display thelistbox
        'on the wrong column
        If KeyCode = vbKeyDown Then
            Call DBGrid1_ButtonClick(DBGrid1.Col)
        End If
    End If
End Sub
'_________________________________________________________

Private Sub Form_Click()
    'hide the listbox if the user clicks elsewhere
    List1.Visible = False 'hide the list
End Sub

Private Sub Form_Load()
    blnListShow = False 'initialize the variable
End Sub

Private Sub Form_Resize()
    'hide the list if they resize the form
    List1.Visible = False 'hide the list
End Sub
'_________________________________________________________

Private Sub List1_Click()
    'insert the selected list item into the dbgrid,
    'and hide the listbox
    If intKeyCode <> vbKeyUp And intKeyCode <> vbKeyDown Then
        DBGrid1.Columns(intColIdx).Text = List1.Text
        'set the value of the dbgrid
        List1.Visible = False 'hide the list
    End If
End Sub
'_________________________________________________________

Private Sub List1_KeyDown(KeyCode As Integer, _
        Shift As Integer)
    'handle the keyboard events
    intKeyCode = KeyCode
    If intKeyCode = vbKeyReturn Then
        DBGrid1.Columns(intColIdx).Text = List1.Text
        'set the value of the dbgrid
        List1.Visible = False 'hide the list
    Else
        If intKeyCode = vbKeyEscape Then
            List1.Visible = False
        End If
    End If
End Sub
'_________________________________________________________

Private Sub List1_LostFocus()
    'hide the list if you lose focus
    blnListShow = False
    List1.Visible = False
End Sub

Create a form With a dbgrid(DBGrid1),and a listbox(List1). 
Populate the listbox with the choices you need the user to 
Select from. Set the visible Property on the listbox to false. 
Set the button property on one of the DBGrid columns to true. 
This example is using column 2. If you want to limit the input 
to the DBGrid to just the items in the listbox, set the enabled 
property to false, otherwise, users can Type in their own data.

Global Declarations within form:
Dim intColIdx As Integer
'This will contain the index For the current cel in the dbgrid

Dim blnListShow As Boolean
'is the list showing or not

Dim intKeyCode As Integer
'the last key pressed within the dbgrid

'selection information. This will simulate a dropdown

'box within the dbgrid. This is an excelent way to

'input specific information into the dbgrid.

'________________________________________________________

Private Sub DBGrid1_ButtonClick(ByVal ColIndex As Integer)
Dim intTop As Integer
'used For positioning the list box for display.

intColIdx = ColIndex
'this is the column of the dbgrid you are in

If blnListShow = False Then
'if the list is not showing then...

blnListShow = True
List1.Left = DBGrid1.Columns(ColIndex).Left + 250
'you may have to play

'with this a little to get it positioned just right.

intTop = DBGrid1.Top + _
(DBGrid1.RowHeight * (DBGrid1.Row + 2))
List1.Top = intTop
'position the list box just below the row you are in

List1.Width = DBGrid1.Columns(ColIndex).Width + 15
'setting the width of

'the listbox to display within the column width

List1.Visible = True 'show the listbox
List1.SetFocus
Else 'if the list is shown, hide it
blnListShow = False
List1.Visible = False
End If
End Sub
'_________________________________________________________

Private Sub DBGrid1_KeyDown(KeyCode As Integer, _Shift As Integer)
'This is to display the list when the user presses the down

'arrow key. This makes it easier to make a selection during

'data entry. The user doesn't have to go to the mouse to

'click the button.

'change the number here to your appropriate column

If DBGrid1.Col = 2 Then
'that has the button, other wise you will display thelistbox

'on the wrong column

If KeyCode = vbKeyDown Then
Call DBGrid1_ButtonClick(DBGrid1.Col)
End If
End If
End Sub
'_________________________________________________________

Private Sub Form_Click()
'hide the listbox if the user clicks elsewhere

List1.Visible = False 'hide the list
End Sub

Private Sub Form_Load()
blnListShow = False 'initialize the variable
End Sub

Private Sub Form_Resize()
'hide the list if they resize the form

List1.Visible = False 'hide the list
End Sub
'_________________________________________________________

Private Sub List1_Click()
'insert the selected list item into the dbgrid,

'and hide the listbox

If intKeyCode <> vbKeyUp And intKeyCode <> vbKeyDown Then
DBGrid1.Columns(intColIdx).Text = List1.Text
'set the value of the dbgrid

List1.Visible = False 'hide the list
End If
End Sub
'_________________________________________________________

Private Sub List1_KeyDown(KeyCode As Integer, _
Shift As Integer)
'handle the keyboard events

intKeyCode = KeyCode
If intKeyCode = vbKeyReturn Then
DBGrid1.Columns(intColIdx).Text = List1.Text
'set the value of the dbgrid

List1.Visible = False 'hide the list
Else
If intKeyCode = vbKeyEscape Then
List1.Visible = False
End If
End If
End Sub
'_________________________________________________________

Private Sub List1_LostFocus()
'hide the list if you lose focus

blnListShow = False
List1.Visible = False
End Sub

Create a form With a dbgrid(DBGrid1),and a listbox(List1).
Populate the listbox with the choices you need the user to
Select from. Set the visible Property on the listbox to false.
Set the button property on one of the DBGrid columns to true.
This example is using column 2. If you want to limit the input
to the DBGrid to just the items in the listbox, set the enabled
property to false, otherwise, users can Type in their own data.