Psions are great fun. They have some of the best utility powers in the game, and some of the most fun combat powers too. (Time hop, I'm looking at you.)
You will want to have a variety of powers. Here's a sample of mine, and the reasons why I took them:
Level 1
- Entangling Ectoplasm: No resist, no save, and only one PP. It's a budget power.
- Crystal Shard: No resist, no save, and reasonable single-target damage. It's my magic missile.
- Mindlink: I'm a Telepath. It's cool.
- Vigor: Pre-combat buff, or mid-combat life-saver.
- Detect Psionics: No Wizard in the party.
Level 2
- Energy Stun: Area attack that's doubly flexible (energy type and stun effect).
- Psi Suggestion: I'm a Telepath, and this is just an awesome power if you're creative.
- Psi Identify: No Wizard.
- Control Sound: We had a Dwarf in full plate. They're not so quiet.
Level 3
- Dispel Psionics: Duh.
- Energy Wall: Flexible battlefield control.
- Time Hop: Best. Power. Evar. I had more fun with this than any other power. "Door? Lock? Ogre? See you soon!"
- Touchsight (Blindsight 60 ft. radius): Hadn't used this, so I'm not sure how it would work out in combat. Took it for a utility sort of power.
... and that took my Telepath through level 6, which is when that campaign fell over.
-- N
EDIT: Oooh, let me tell you about my feat choices, too:
1 lev- Point-Blank Shot (for Crystal Ray and xbow)
1 hum- Boost Construct (for L3 feat)
1 psi- Psionic Body (2 hp per Psionic feat, which is all of these except point blank shot)
3 lev- Expanded Knowlege (Astral Construct)
5 psi- Psionic Meditation (recover focus quickly)
6 lev- Psionic Shot (expend focus to deal +2d6 ranged damage)
Now, the big trick with Psionic Shot is this: use it with Crystal Shard. Expend one PP and your Focus, and you have a touch attack that deals 3d6 damage (no save, no resist) for only one PP. That is what I call a good deal! Alternately, blow your wad (6 pp) for 6d6, and your focus for +2d6, for a total of 8d6 at 6th level. Not bad.
The obvious use of Psionic Shot (bow or other ranged weapon) isn't too bad either. It's nice to have a back-up plan when you're low on PP. It means that an Elf Psion is kinda cool.