Bob Conant's mention of ASCAP prompts me to mention the equivalent
organization here in the UK: the Performing Rights Society (PRS).
They issue a licence for an annual fee of around 20 GBP to any bona
fide amateur organ grinder who plays in public.  This covers royalties
to any copyrighted music played, with no play list being required.

Regards,
John Page, UK
Membership Secretary, Fair Organ Preservation Society
http://www.fops.org/