Small but useful little device I just made:
Gradually fade between different tempos by naming your scenes appropriately - ie by launching the scene named XBPM 150 the set will gradually change tempo from your current tempo to 150 bpm. The rate at which it changes is dependent on the size of the gape between tempos - ie larger changes in tempo take longer.
http://www.maxforlive.com/library/device.php?id=305