Yes, Kids can go on any cruise line but they will have more fun on some compared to others (like I would never think of taking a child on a Princess, Celebrity, Costa or Cunard cruise).
Carnival and Royal Caribbean (maybe even Norwegian) all have a kid area where you can drop the kid off for them to play. Sort of like a in house day care romper room thing. If memory serves me correctly, you do not have to pay.
Also, they have arcades on the ships for the kids (not free) to let them get their video game fix in.
phlydude  (aka Dennis)
"I only hope that we don't lose sight of one thing - that it was all started by a mouse" Walter Elias Disney