NeatGametap will start to offer games to download on the same day as their release, starting with Tomb Raider: Anniversary. Not all games will be like that, but its still kind of cool.
GT will also have an online store where you can purchase and download games to own, instead of their regular subscription model. Again, not all games they offer will be part of this, but as one site mentioned even if they only had a fraction available they'd have as many or more titles than Steam.
And lastly, free accounts! Theres regular random user free, then the registered user free (Green accounts), and their regular pay stuff. Supported by banner and video ads. Starts May 31 with these titles: Taito's Bust-A-Move and Space Invaders, SNK Playmore's Metal Slug, and Midway's Joust, Robotron: 2084, and Rampage to Crystal Dynamic's Lara Croft Tomb Raider: Legend. Don't know about you guys, but I am so playing TRL for free.