[1] : WordNet (r) 2.0

soapbox
     n 1: a crate for packing soap
     2: a platform raised above the surrounding level to give
        prominence to the person on it syn: dais, podium, pulpit,
         rostrum, ambo, stump
see also:
dais podium pulpit rostrum ambo stump 

[2] : Moby Thesaurus II by Grady Ward, 1.0

29 moby thesaurus words for "soapbox":
   balcony, catafalque, dais, declaim, emplacement, estrade, floor,
   gallery, harangue, heliport, hustings, landing, landing pad,
   landing stage, launching pad, mouth, perorate, platform, podium,
   pulpit, rant, rave, rostrum, stage, step terrace, stump, terrace,
   tribunal, tribune

Soapbox >> S Words
Soapbox, definition of term: Soapbox
soapbox_pag1.html