Sorry to pull this thread from the dead, but what about eldritch heritage? Now normally we don't get too excited about a bloodlines' 1st level powers, but what so many folks are discussing here is essentially a filler action where you hope your summoner casts a couple of spells and spends filler actions that do something - hope the bow shot hits even if it doesn't do much damage and the like.
A handfull of the bloodlines can provide a reasonable power to fill that gap. With the summoner's CHA it should provide at least 7 uses per day.
Bedrock/Deep Earth - gives you a 30' range trip ability (decent skill focus and Iron Hide later with Bedrock)
Seaborn gives you a water blast gives you what is essentially another ranged trip ability (swim as skill focus, OK if situational later power)
Protean provides a tanglefoot bag essentially. (Planes as the skill and reality wrinkle later).
Groveborn gives you a 15' trip or disarm (nature is the skill and lush summons is the later power you can grab at 11th to add +2 natural armor to your summons)
Maestro is pretty cool. It gives you a 1 round daze limited by language (you should have a lot) and HD (you're stuck with perform as your skill but perfect voice can be nice later).
Accursed gives you horrific visage (perception! as the skill focus and dread gaze at 11th).
Primal is mildly tempting with a ray, but only because you get to add elementalist summoning at 11th (+d6 to all 5 attacks from your celestial dire tiger probably isn't necessary, but hey, why not)?
Not bad options for a master summoner.