....pay your bill and buy Bitcoin at the same time with a Bitcoin merchant. ....
Like this idea very much. Might be easier for the merchant too, to save them one conversion transaction. Plus not having to run to the bank to get change coins.
Good way perhaps to spread the gospel: even if the customer has no history of Bitcoin usage, an instant paper wallet could be generated. With the growing faascination, an instruction poster on the wall, or a quick conversation could gain another convert. People who would otherwise not venture into this world (localbitcoins, meetups, various exchanges etc.).