Sounds a good idea.
A few thoughts
There are a few categories that concentrate on sports stadia, (not clubs) so you'd need to read those categories to make sure yours isn't redundant.
Do you intend to include both pro and amateur?
School/college or just clubs?
Where would you waymark? The club house? The ground?
What about clubs that don't have a home - here in the UK there are quite a lot of clubs that don't have their own facilities (eg pub teams).
Pro teams sometimes separate training grounds.
What constitutes a club? Does it have to be registered with the sports governing body?
I'm not trying to be negative, just thinking up questions you might want to address.
And lastly ... on a personal note do Charlton Athletic actually count as a club, when they are so depressingly bad? :( :(