One of the big white good retailers in Australia uses the slogan "Pay Less. Pay Cash!" as a means of encouraging sales.
Since BitCoins are analogous to cash in many ways, perhaps we small businesses can adopt a similar system on our customer invoices as a way to encourage people to use this currency.
I'm considering doing this for my own business since I wrote the accounting software I use and it's only 30 mins work to add it.
The catch 22 at the moment is that there are no AUD to BTC services in Australia that I know of which defeats the purpose somewhat. (I'm still considering setting one up like BritCoin, but not sure how to approach that yet due to potential legal issues, plus someone might beat me to it!)
Anyway, what do you think?