A PC for 99 $: the E-Way TU Tiny 200.

Tiny (dimensions: 11.5 x 11.5 x 3.5 cm; weight: 500 g.) has 128 MB Ram, a fanless 200Mhz CPU, 3 USB ports, and a Compact Flash slot; includes LAN, VGA, and audio.

The TU Tiny is compatible with Linux (for example with Puppy Linux, that runs using a 128MB USB Flash Card).

See also: the NorhTech MicroClient Jr, that share the same concept and design.