Tuneglue is a great web tool to find other bands and artists that are similar to your favorites. You just type in the name of a band and the band appears on your screen with a circle. Click on the circle and you have the option to view the album releases from that band or "expand" which connects the original band with other bands that are similar, creating a web or map of bands.
For example, when expanding the band Kings of Leon, the following artists are connected:
White Lies (currently opening for Kings of Leon on tour)
Cold War Kids
You can argue how much these other bands are really similar to Kings of Leon, but it is a fun tool to discover music you may enjoy.