You can get table names from the MSysObjects system table (usually hidden), and use the following SQL syntax to access an external database.
Code:
Private Sub Form_Load()
Dim sSql as String
sSql = "SELECT [Name] " & _
"FROM MSysObjects IN 'C:\someother.mdb' " & _
"WHERE Type=1 and Flags=0 " & _
"ORDER BY [Name];"
Combo0.RowSource = sSql
End Sub
This example assumes that the external database doesn't have passwords or login details.