Summary Box: MOG, Rdio Enter Mobile Music Field

JOIN THE CLUB: Music blog site MOG and startup Rdio are offering ways to stream millions of songs to mobile devices for about $10 a month.

STANDOUT SERVICES: MOG touts its slider control, which toggles how many randomly selected tracks come from a single artist or many similar ones. Rdio mixes social networking with discovering music.

WEB ONLY, TOO: Both services also have a $5-a-month plan for computer-based usage, although MOG is also planning to throw in the ability to listen via a TV connected to a Roku set-top box.