Another vote for the 18-200 here, although with reservations.
As far as superzooms go it's one of the best out there, but what you have to remember is, that due to it's wide range, it's a lens full of compromises. That said, these compromises only really become apparent if you are used to the more dedicated lenses on offer, and even then a good proportion of the problems this lens presents can be effectively cured in post processing.
If you're just starting out in DSLR photography and just want to try a bit of everything then this lens is a great catch all, and for some people it really is the only lens they'll ever need. On the other hand if you already know what subject material interests you then there will be better lenses that apply directly to that subject material.
So, I guess the question is: what do you see yourself photographing? If the answer is it's a bit of everything until you find your niche then the 18-200 is a fantastic start. If, on the other hand, you already know what interests you then let us know as we'll be able to suggest a more appropriate and better lens for the task in hand.