For a current list of the gears look at hedgewars/uTypes.pas at
the TGearType enumeration.
http://code.google.com/p/hedgewars/source/browse/hedgewars/uTypes.pas#89
{{{
    TGearType = (gtGrenade, gtHedgehog, gtShell, gtGrave, gtBee,
            gtShotgunShot, gtPickHammer, gtRope, gtMine, gtCase,
            gtDEagleShot, gtDynamite, gtClusterBomb, gtCluster, gtShover,
            gtFlame, gtFirePunch, gtATStartGame,
            gtATFinishGame, gtParachute, gtAirAttack, gtAirBomb, gtBlowTorch,
            gtGirder, gtTeleport, gtSwitcher, gtTarget, gtMortar,
            gtWhip, gtKamikaze, gtCake, gtSeduction, gtWatermelon, gtMelonPiece,
            gtHellishBomb, gtWaterUp, gtDrill, gtBallGun, gtBall, gtRCPlane,
            gtSniperRifleShot, gtJetpack, gtMolotov, gtExplosives, gtBirdy,
            gtEgg, gtPortal, gtPiano, gtGasBomb, gtSineGunShot, gtFlamethrower,
            gtSMine, gtPoisonCloud, gtHammer, gtHammerHit, gtResurrector,
            gtNapalmBomb, gtSnowball, gtFlake, gtStructure, gtLandGun, gtTardis);
}}}
Note: gtBomb and gtShell were named gtAmmo_Bomb and gtAmmo_Grenade before 0.9.14