Here's a little secret that T-Mobile didn't really intend for public consumption: if you give the company a ring you can nab an extra $100 off a G-Slate. The discount was emailed out to those who signed up for a special promotional offer T-Mo teased recently. Like most things, though, the internet got ahold of this juicy morsel and we're happy to tell you it's open to everyone. Just reference promo code GSLATE100 and you can pick up a shiny new Honeycomb tablet for $430 -- provided you have an existing voice plan or sign up for one, are willing to commit to a two-year data contract on top of that, and don't mind dealing with a mail-in rebate. If those caveats don't scare you off, go ahead and call. Just act quick, the offer ends April 27th. Check out the larger image after the break for full instructions.