I've come up with an idea for a new BIGBY/green birding category: incidental birding.
Basically, it's keeping a list of birds seen while traveling for non-birding purposes. Say you are going to visit family on a holiday, or are required to travel somewhere for business, etc.
Once you get to your destination, you can only count birds according to the usual BIGBY rules, but it's OK to plan the trip itself so that your route takes you past birding areas along the way.
For those of you unfamiliar with BIGBYing and green birding, here's some info: