www.ultimatecampresource.com has lots of ideas for games. I have found ideas from looking in catalogues for party stores or suppliers like S&S, I google things like "camp special events" or "pirate day" etc. just to see what pops up. Sometimes you can get ideas from knowing a little about your audience- you know that your kids like Harry Potter so it would probably not be too difficult to keep them entertained by having HP themed week.
I know planning the actual events for the week is tough when you don't know where to start, so I guess the questions I would consider are: What/how can I decorate? What games can we play/ can I rename games I already know to fit in with the theme? Do we know any songs? Can the menu reflect the theme? How much money can I spend? What can I use that we already have?
I try hard to involve lots of other people in the planning because special events and theme weeks take so much energy. If you like, check out this link:
http://www.campmohawk.org/newsite/publish/overnight_events.shtml they're not weekly themes but some ideas for special events. Hope it helps!
