The Seven is essentially a variation of The Eleven. It is in 7/8 and the main grouping is 123 12 12, although it switches around a good bit. There are only four known performances of The Seven(according to Deadbase VII) and two of those were Mickey and the Hartbeats shows.
Estimated Prophet is in a slow 7/8. On some tapes, especially on early versions, you can hear Bobby count to seven to start the song.
Playing in the Band could basically be in 10/4 hence its original name The Main Ten. However, for more practical notation purposes it would likely be written in 5/4. In time signatures where the quarter note gets the beat it is generally common practice to not go over 5 beats a measure. 7 is used occasionally, while 6 is better written as two 3/4 measures.
Other songs, such as the Other One, that might sound like they are in odd meters are actually not. Their rhythmic complexity is derived from accents on off beats. Unusual accents also add further to the complexity of Playin'. [Thanks to Michael Bell mbell@mail.utexas.edu for the above info about The Eleven]