# Sharing list data between sites

I have a list on a sub-site that I want to share via Drop Down List with a Calendar on the root site. ie. When you add or modify a Calendar entry, one of the columns will be a Drop Down List populated by the Title column of the List on the sub-site.

What is the best way to do this? A DataView Web Part might be able to, but that looks really complicated and seems to require Visual Studio when I'd rather just use SharePoint Designer if possible. The other option is using BCS, but due to the way the SharePoint Databases work, there isn't a single table where I can pull the values I need. I could probably do it via a View, but I still don't know where these list items are stored which makes this a difficult option too. Is there a 3rd option I have missed or are one of the other 2 my best bet? This is on 2010 Foundation if it makes a difference.