Does anyone have suggestions on how to go about merging multiple lists (with the same columns) within a site collection into a master list?
I agree with Mike that the Data View Web Part, used in crosslist mode, is your best bet.
If you are working with tasks lists, you can directly try out this DVWP builder: http://blog.pathtosharepoint.com/2010/05/25/tasks-lists-roll-up-beta-available-for-download/
There are lot of such solutions like SharePoint List Collection in addition to Data View Web Part. The problem of that is those solutions pull date from other lists into a view. Not meet your requirement of merging multiple lists into a master list. Did you give a try to lookup functionality of SharePoint if you are using SharePoint 2010.