Various notes on Jeff's suggestions:
Crystal Shard: Is only good if you ignore the godawful C.Psi like the plague.
Energy Ray is nice, but I don't see a need to get it AND crystal shard, since you start kowing so few powers. Also, at later levels there is Energy Stun and possibly Energy Missiles (if a Kineticist or by feat).
I'd say Astral Construct is worth it for any psion. Even if you need to take a feat to get it, it gives a lot of versatility, since instead of a different summon version each level, you can just augment the same level 1 power.
Vigor: Not only for 5 hp, you can also augment it to basically get +5 hp / PP, though new usages overlap. It can be a bit tricky to use well with the short duration, but it can give you a LOT of temp hp to soak up damage with if cast early in a tough fight.
Other useful powers to learn (i'm going to assume a psion or wilder):
1
Psionic Daze: Scales the HD with PP, though the save DC will quickly suck. Might be good early on, if your DM lets you replace powers like a sorcerer.
Demoralize: For a single measly PP, you have a useful area debuff that won't affect allies. Special: If your DM is cool with the transparency rules, telepathy is basically enchantment. Complete Mage has an awesome feat called Unsettling Enchantment. Whenever you use an enchantment spell on a foe, even if he makes the save, he suffers a minor penalty for a round (-2 AC, iirc). Combine this feat with Demoralize and you have by FAR the most cost-effective psionic combo you could get. Any round you want, for just 1 PP, you get a great area debuff.
Disable: Useful if your DM doesn't frequently "metagame." Also if he uses enemies besides the crazily berserk "fight till I'm dead" variety.
Psionic Grease: For all the reasons the arcane version rocks.
Psionic Charm: Telepath power. Useful just as the arcane charm spells are.
Mindlink: Telepath power. I like being able to secretly communicate with allies. Works fine on a power stone if you don't want to learn it.
2
Energy Stun: It's only good for augmenting, as the base damage is crud. But the save DC scales amazingly well with more PP.
Specified Energy Adaptation: Sucks that it's self-only, but energy res is helpful, and for added cost you can throw it up on the spot.
Energy Missiles: Same deal as Stun for save DC, and does good damage. You either need to be a Kineticist or spend a feat, though (it's worth a feat).
Psionic Repair damage: Shaper power. Only useful if playing Warforged or such, but if you are...this is actually WAY better than the arcane versions and pretty darn good healing, even compared to divine magic.
Brain Lock: Telepath power, and lasts for concentration. It's basically will save or lose, useful if your party outnumbers the enemy. Save will suck later on, though. And you do kinda just have to sit there while your party finishes the job.
Psionic Suggestion: Telepath power. As useful as arcane version.
3
Dispel Psionics: No need for a higher level version like with Detect Magic, and I'm pretty sure you can use it against magic via transparency rules. And if you can't...that means enemy mages can't dispel you, so win-win.
Energy Bolt: If you're not a Kineticist, this is one of the best area damage spells you can get without a feat.
Psionic Blast: Be a mind Flayer! Great with Extend.

Time Hop: Can both be used to divide and conquer as well as to get a troubled ally out of harm's way for a while.
Hustle: Egoist power. Can be combined with the Psionic Meditation feat to gain your psionic focus twice in the same round.
Ectoplasmic Form: Egoist Power. Lower level than Fly and offers nice protections, so long as you can make the concentration checks to manifest powers, it might be better. The only thing higher ML gives is duration, and it likely won't last more than an encounter anyway, so instead of learning it if an Egoist, consider just using power stones of it.
4
Death Urge: Gets bonus points for hilarity. Probably not worth the massive augmentation cost to improve. Probably not even worth learning, but...so funny!
Psionic Dim Door: Because you're squishy and don't like hugs.
Telekinetic Maneuver: Not worth augmenting, and only worthwhile if you plan to keep it going a while, but still quite handy and versatile.
Psionic Freedom of Movement: For same reasons the psell version is good. May not need this AND dim door. This also works fine as a power stone, though somewhat pricy.
Psionic Fly: Nomad power. Kinda sucks that it's higher level and self-only compared to Fly, but if you happen to be a Nomad, it's still a nice thing to have. I'd not waste a feat on it.
Control Body: Kineticist power. Fort save or lose. The DC doesn't increase, sadly, so might be useless later on, and many things have high fort anyway. But it's potentially so much fun!
Psionic Dominate: Telepath power. Useful as arcane version.
Schism: Telepath power. More actions per round = MOAR P0\|/3R!
Metamorphosis: Egoist power. It's polymorph, that's reason enough to want it. Also, the
feat for it...