Here is a list what you can summon:
Monsters...
summon pack.BPupae
summon pack.MTProj (Mirror tentacle projectile)
summon pack.Gbag
summon pack.Starman
summon pack.StarmanD (Starman Deluxe)
summon pack.Mqueen
summon pack.MTentacle
summon pack.TTrooper
summon pack.BIGSkaarj
summon pack.FTitan (fire titan)
summon pack.SLITHER

Items...
summon pack.BBelt (a shield belt that makes player look big)
summon pack.MBoots (new kind of jumpboots)
summon pack.redbelt (red shield belt)
summon pack.SLight (spot light, only used by admins to light up dark levels) :)

Weapons...
summon pack.Flamer (Flame Thrower)
summon pack.RockRifle (weapon that throws rocks)
summon pack.MBall (99 Ball, not eightball, can shoot up to 99 rockets in same time)

Ammo...
summon pack.Fuel (needed by flamer)