Tapbot's blog [1] is nice. Not make-you-weak-in-the-knees-pretty, but it looks interesting enough to raise curiousity, which is what you appear to be after.
Write a Brainfuck interpreter. Seriously, it is trivial to write a simple one, slightly harder to write a compact one, and then just hack on to optimize it for speed. There are great test cases too including ASCII Mandelbrot renderer :)
Thin phones are not practical. I can tell that as a proud former owner of Samsung Ultra -- 7 mm thick -- that broke in half when I forgot to take it out of the back pocket and sat on it. It was a delightfully elegant phone, but very fragile.