My wife and I have found a great sale on marble tile and thought we might like to use it in the kitchen. We brought a box of tiles home to put on the counter to get an idea of how the finished product would look. Cooking oil from a pan got onto one of the tiles and stained it instantly. Is marble just a bad choice for kitchens, or are there sealants that are effective enough to protect the surface from normal spills and wet stuff?

Marble is pretty but granite is much, much less porous. You can seal marble but you'll need to retouch every year. I would not use it for a kitchen counter top, go with Corian or granite.