Another mum of a non-talker here! DS2 has just turned 18 months and until about 2 weeks ago had no words at all. Yesterday we counted 12 words - some are stretching it a bit! (Daddy, Mummy, Beep beep [car], choo choo [train], Hiya! [Vicky Pollard style], Boo!, quack quack (only it's more like "Dak dak"), a "clip clop" noise for horses, Baby, "Me me me!!" [accompanied by wild pointing at whatever he wants], "Dip dip" (while dipping food) and Geese. Of these, only daddy, mummy, hiya (unfortuantely), boo and baby would be clearly identifiable to strangers.
I am not worried - he has been referred for a hearing test but only because of his personal medical history (he was referred for having no words at 16 months, if it hadn't been for his medical history I doubt they'd have bothered). He does everything on messtin's list - is big into pretend play, and physically very advanced (especially compared to DS1 who was an early talker but slow to walk).
cakesonatrain - my DS2 has been a big babbler too, has "chatted" nonsense for months, we've started tuning into his chat a bit more and there are actually a few words in there that I wonder if he's had for a while and we've just missed (lots of his vowels are wrong - so "dip dip" sounds more like "dap dap").