Using Parallax Propeller chips
I have a few chips, but haven't really gotten to use them.
I set up a barebones Propeller board (blog) to test, with some success. There is no EEPROM for non-volatile program storage, so it's purely for RAM toying for now.
CP2104 USB adapter works nicely as an interface.
Supply voltage range is 2.7 – 3.6 V.
Important GPIO pins at boot:
P28 - I2C SCL connection to optional, external EEPROM. P29 - I2C SDA connection to optional, external EEPROM. P30 - Serial Tx to host. P31 - Serial Rx from host.
Crystal should be fully static DC - 80 MHz or, if using PLL, 4 - 8 MHz. 5 MHz is popular. There's more information in the manual, under clock register setup.