Making a fun Psionic Summoner PrC

[Yora]

I want to make a Summoner prestige class for psions, that is somewhat similar to summoning in Final Fantasy.

Making very powerful summoning spells would be the quick and dirty way, but that does not seem either balanced, or fun to play. Just giving the player a second character with awsome abilities slows things down and and is probably not too fun for the other players.

Planar Ally seems more along the line, but takes too long to cast, lasts for more than an encounter, and has Gold and XP costs.

My current idea is to start with the Astral Construct power (refluffed to summon spirit, but that doesn't change the mechanics) and then pack together a bunch of class features that greatly improve the strength of the creature.
Unfortunately, I don't have much experience with handling summoned creatures, as I it happend only once in my entire time of playing. And it was just a 3rd level character.

So even before I start with designing class features, what things should I be aware of and what do I have to consider when making a dedicated summoner class? What things slow play down and become an anoyance to other players?

Any help is highly appreciated.

[Eloel]

This

I don't know how helpful I am, but that's what you're looking for.

[Dragon Elite]

You could see my Mad wizard for ideas. I like the idea.