Polymorph items

[Mendicant]

Other than a greater hat of disguise, what magic items let a character change into other things? I'm particularly looking for an item that allows someone to turn into a tiny animal, or advice on pricing a custom item that does that.

[Psyren]

Skin of Proteus (http://www.d20srd.org/srd/psionic/items/universalItems.htm#skinofProteus) - slotless at-will metamorphosis

[Darrin]

Other than a greater hat of disguise, what magic items let a character change into other things? I'm particularly looking for an item that allows someone to turn into a tiny animal, or advice on pricing a custom item that does that.

Cape of the Viper (2000 GP, MIC) can turn you into a small viper for 7 rounds.

Phylactery of Change (11200 GP, A&EG) can polymorph you into most any creature up to 7HD, indefinite duration.