If you have an iPad I highly recommend getting LiquidSketch. It's a great puzzler about getting pools of liquid into the right place, and the liquid effect is stunning. It moves exactly as expected, has surface tension, splits and recombines etc - but the really stunning element is colour mixing. When two groups of different colours combine the mixing of them is just utter convincing, and beautiful. Amazing how this was all done on a lowly iPad.
When you say "on a lowly iPad", bear in mind that the latest (4th-gen) iPad has a dual core 1.4 GHz chip plus a GPU capable of 14.4 GFLOPs. It's actually a pretty powerful machine.
Real time raytracing is vary doable and high quality, it's just we got really good at rasterisation. Consider a 2012 demo http://www.youtube.com/watch?v=h5mRRElXy-w it's cool and all but what seperates it from rasterisation is fairly subtle and the computing costs are rather high.
You can totally do real-time raytracing. I wrote my first raytracer a couple of weeks ago — http://canonical.org/~kragen/sw/aspmisc/my-very-first-raytra... — and it gets about 4fps on simple scenes on my netbook, despite being the product of only a few hours of work. If you use a GPU and/or SSE and/or a faster CPU, you should easily hit full-motion video.
My netbook is probably half the speed of an iPad.
It would be fun to put together a custom OS-less AMI to raytrace partial frames in realtime on EC2. 20 instances spun up in a few hundred milliseconds could do pretty substantial real-time raytracing.
Alternately, do lots of bounces with fewer rays, decrease the total dynamic range, and add a consistent noise/grain filter. Realistic raytraced night-vision :)
The CPU pulls tens of GFLOPs in single precision, too (and > 5 GFLOPs double precision!) It’s at least as powerful as any desktop you are likely to have had a decade ago.
I had the same concern, but after having a mini for a while, I can tell you that I don't notice the lack of retina resolution at all. They hold their value really well too - I highly recommend just getting one now and selling it once retina comes out.
