A sort of challenge/project for myself (Dakotas-involved)

[Verily]

Here's the most difficult thing: You would need Park County to include Teton, and Park's margin for McCain was actually larger than Teton's for Obama. Still would probably be a must.

As your own map shows, you don't actually need Park County to include Teton and make it contiguous, although without Park the district looks much uglier. You could probably get the red district to more than 50% Obama with some fiddling along the edges (exchanging some stronger McCain counties for weaker ones).

[Verily]

Pomeroy lives in the west, Herseth lives in the east, an if you look at previous results and maps, both could easily win the western district.

True, though the fact that Pomeroy has had joke opponents, which would perhaps become less likely with this configuration, probably has something to do with it.

The Montana/Wyoming gerrymander would probably give the Dems a good shot at one seat. Do either of the Reps from those states live in that Obama district?

Rehberg lives in Billings. (Yes.)

[Verily]

Well, here's the New England (+New York) municipality map. Have fun trying to craft a McCain district out of those results. You probably could do it, connecting the Republican areas of northern and eastern Maine through the uninhabited areas to central-southern New Hampshire and then in a collar around Boston through Worcester County to get the South Shore towns.

Those might not even be necessary; NH-01 was not that strong for Obama, so replacing the Portsmouth area with Republican areas in Maine and northeast Massachusetts could suffice.