Did you know that you can use an xBase expression as a picklist item?
You simply need to add the expression to the picklist, prefixed by a tilde (~), like this:
Try it yourself; let us imagine we have a value in KEY1 that we'd like to easily copy to the Activity Code of a new history item.
1. Select Complete | Unscheduled Call | Outgoing Call.
2. Bring up the Picklist for the "Code" box by clicking into it and hitting F2.
3. Click "New"
4. Paste in the following text as the new picklist item : ~contact1->key1
Now when an end user selects that item from the picklist, it will copy in the value from the KEY1 field. Any Contact1 or Contact2 field is allowable. Have fun!