My parents are born in Hong Kong so I can speak Cantonese semi-fluently, although I cannot write.
I've been learning Mandarin and I find that my cantonese has been useful because if the word is used in Cantonese as well, its fairly easy to know the usage.
I find that a lot of the times I'm translating Mandarin into Cantonese into english basically.
I was wondering if anyone has come across a voice program / website similar to Google translate, which allows you to enter some characters in and it'll say it in Cantonese. All the ones I've come across so far speak in Mandarin.