I have never really worked that much with lookup fields to connect lists before. Usually a choice field and/or a managed metadata field is enough. Now a customer requested a couple of lists that were connected to eachother. "No problem" was my initial response, but yet again SharePoint would take me on a journey down the road of frustration.
The customer needed one parent list and two child lists. The parent list should display the title field and some choice fields from the child lists. Sounds really simple. When I started creating the lists I quickly discovered that it is impossible to use choice fields as lookup fields. The workaround is both simple and brilliant, see http://bramnuyts.be/2011/04/05/using-a-lookup-field-on-a-choice-field-workaround/. Now it works just as the customer wanted, as long as you hide the calculated fields in the default view and the item display form.
Yet another day in SharePoint paradise...
