Summoners in D&D...

Ok. Lets say you were going to go for a summoner. Someone who can conjure a variety of monsters to battle/fetch/guard/whatever. Using the current D&D system (and any optional rules that don't gut the system.) how would you go about it?

What class: Wizard, Conjurer, Sorcerer, Cleric, Druid, Mystic, or something else entirely? What about domains or forbidden schools?
Any good Summoner PrCs? Aside from Alienist and Thaumatergist?
Feats? Useful Skills?
What spells beside the obvious Summon Monster or Summon Nature's Ally are there?
Useful D&D supplements and d20 Supplements?
BIG ONE: How would you go about role-playing him/her? What summoner mindset traits would exist?

THere are a few feats from different sources like Augment summoning. There is a summoning prestige class I realoly like from Path of MAgic. Extend Spell is also another good feat for the spells.

To get on to the role playing part, I'd play him as a confidant person knowing they always have the right tool for the right job. With the vast amounjt of creatures the character can bring forth he can conjure whatever will be the best for the problem no matter if it mundane, combat oriented, or whatever. The character would be cocky and show off their vast summoning skills to solve even the simplist of problems.

Druids make the best summoners in 3.5. They can spontaneously change any spell into a summon nature's ally spell.
RP wise I peronally prefer a wizard specialist in conjuring.

Phantom Steed is a cool wizard summoning spell. Good for long distance transportation and really neat looking.

In Defenders of the Faith there is a "Summoning Prestige Domain". Definately something to go for on the Divine side, if your DM allows it.

As for personality I always see good-aligned Summoners as the ultimate Diplomats and charismatic types. Creatures summoned recognize that they are serving a good purpose through the actions of the caster or the results of their work. (or fast-talking of the caster...)

I see Neutral casters as contracters. The spell is a contract, I summon you and you do this. That's just how it works.

I see Evil casters as controllers/dominators. They gleefully summon whatever and force it to do their bidding (with the occaisional evil cackle). They're the ones who think summoning Baatezu to fight halflings is not only a good idea, but also a lot of fun.

Just my 2 coppers

I prefer clerics with the Summoner domain(Tritherion if you're using standard Greyhawk cosmology), since wiz/clerics get access to vermin and outsiders, and druids just get animals and elementals/elemental outsiders. Also, if you're playing a cleric, you can swap your unwanted summons for cures, which can be slightly better than memorizing cures and swapping for summons(druid). In terms of feats, SFC/Augment Summon makes slightly stronger creatures, Beckon the Frozen from Frostburn gives your summons the cold subtype and +1d6 cold damage to their attacks. Taking Rapid Spell, then Divine Metamagic(Rapid Spell), both from Complete Divine, lets you cast summons as a standard action by burning 2 turn attempts. Celestial/Fiendish Summoning Specialist from Planar Handbook can add additional creatures to your summon list.

In terms of prestige classes, both Alienist and Thaumaturgist are good, though Alienist is good for animal summons, and Thaumaturgist is good for outsider summons.

I'm surprised that nobody's mentioned shaper psions yet. The Astral Construct power lets you conjure a very customizable construct, which is pretty nice. Still, I like the flavor of conjurer wizards and thaumaturgic clerics.

Demiurge out.

Heres a couple of hombrew variants created by ENworlder frankthedm

Shocker Lizard I choose You!

FF Summoner

For arcane summoning, I prefer a Sorcerer. Simply because you get to keep casting summon monster more times than a wizard/conjurer ever could. On the flip side, you have fewer spells overall, so you need to be careful about which other spells you take.

Your feat choice will also be important. Augment Summoning, Extend Spell and Spell Focus (Conjuration) are a must. Stuff like the feats that let you add subtypes to your summoned creatures are useful. And avoid PrCs that don't enhance your spell progresion, as that's the only thing keeping you in line with the other PCs power level.

Summoner Stuff

The summoner brings things from somewhere else to where they are.
This is probably best handled through arcane casting, and I prefer sorcerors.
The Summon Monster spells are iconic.
Other good spells include:
Mount
Phantom Steed
Dancing Lights
Shield (Summoning a disk of force)
Phantom servant (summoning a force servant, again)
Floating Disc (turn your shield disk on its side)
Levitate (now you can stand on your floating disc)
Arcane Eye (summon an eye)
Magic missile (conjure missiles, possibly disc-shaped, and launch them at targets)
Resilient Sphere

Get planar languages: you'll need them to communicate with your minions and direct them in their work.
Get the Firey Dragon summoned monsters counter pack if you use minis.

One possibility:

The savage bard from unearthed arcana. Why savage? Because summon natures ally is better (in combat terms) than SM - SM is good for utility and not a lot else...

Bard so you get those nifty bonuses to your summonees, and also so you're not alignment limited in what you summon. Pick up focus(summoning) and improved summoning, and all the bardic music boosters (ironskin chant is neat for instance).

Maybe not as good as the stereotypical druid, but a bit different and possibly more versatile (in terms of stuff other than spells).