First up, Space Miner was chosen as our Daily App a while back -- it's a very cute, well-written arcade/sim title that has you flying around collecting ore from asteroids to build up your uncle's space mining business. Now, Space Miner Blast brings the title to the freemium realm -- it's a free download with ads, and you can pay for premium ships to both boost your abilities and get rid of the ads. There's also Game Center integration and full Retina Display graphics, so even if you haven't tried the Space Miner series before, this one's worth a try.
Trade Nations is also making some waves lately -- it's a city-building game in the vein of Farmville and We Rule, with a little more mature art style than either of those. You can create jobs for your own villagers, and even participate in an online marketplace, where prices for goods rise and fall according to supply and demand. Seems like fun -- the whole thing is driven by Mojo-style in-app purchases that just shorten the amount of time it takes for a project to complete. Freemium as a concept is really coming into its own on the App Store, and the more quality titles we see that use this model, the more customers and audiences grow accustomed to how it all works.