Gamboge, rouge.

OGUE.

(As in "rogue"), rhymes vogue, prorogue, collogue,* disembogue. (As in "catalogue"), rhymes OG.

OH.

Oh, rhymes OW and OWE.

OICE.

Choice, voice, rejoice.

OID.

Void, avoid, devoid, asteroid, alkaloid, etc., and the preterites and participles of verbs in OY.

OIF.