For those who can still get their congregations to add a service this week:
Here is the 1945 Minhat Todah- Service for Thanksgiving Day, Congregation Shearith Israel, NY by Rabbi David de Sola Pool.
Happy Holiday- Let me know if anyone uses it.
Thanksgiving Service- 1945 Rabbi de Sola Pool (pdf of full service)
There are several good sermons from Rabbi Leo Jung for Thanksgiving Sabbath and a couple of shiurim on the web from Rav Soloveitchik from the Wednesday on the eve of Thanksgiving. Here is one of my favorites from Nov. 22, 1975