Check out Roine's solo work. More specifically The Flower King, unofficially, but arguably the first Flower Kings album, and Hydrophonia, which is a great instrumental album, and unfortunately it is rare. Wall Street Voodoo is somewhat of a homage to his roots. It's a bluesy rock album.
Kaipa is also something to look into, but I'm not very familiar with them.
The Tangent is great. The most jazzy of the Roine Stolt related groups. Roine was part of their first two albums, but not the new one. Nevertheless, I highly recommend you check that one out as well.
Other than projects that Roine has been a part of, I can't think of any bands that bear more than general sound similarities.
Edited by Moatilliatta