In reply to Carmengr21:
I worked on a fairground on the beach for a few years, the most popular ride by far was the bungee/trampoline, you put the kid into a harness, attach them to some bungee cord and let them bounce, an artificial climbing wall has similar appeal.
I don't think you'd get much interest from climbers who are looking for somewhere to spend the day climbing, but you'd get interest from families, or just people having a day out, or teenagers who want to show off to their mates/girlfriends. Make the routes easy and colourful, maybe stick an auto belay at the top and in Summer you'd get lots of interest.
A big challenge is how to make it safe, you have to assume that the customers are going to misbehave and break the rules.