If the sector is tourism, there's plenty of space for verticals. I have a client who has a ring of sites offerinf holydays for board sposrtsers: surf, kite, snowboard and the such. Sambeau suggested cyclists. Another idea could be: travel for families with children. Travelling with children can be hard, especially if the destinations are exotic and the children are small; so a website featuring advice on this topic might have an audience.