As you can see there's been little response and so far not one single concrete idea.
Well let me tell you why I like the Arduino. It might not be the fastest thing in the world, but remember the original IBM PC ran at 4.77 MHz. So at 16 MHz it's not too shabby,
You don't have to download DLLs onto it. You don't get viruses. You don't have an operating system so complex no-one can comprehend what it does. It boots in about a second, or less. It shuts down by yanking out the power cord. It's powerful enough to talk to SD cards for massive data storage. You can interface LEDs, motors, rotary encoders, LCDs, a huge amount of things. It's cheap. The Arduino IDE in particular makes it very easy to program. Properly configured, it can use a tiny amount of power when inactive.
You compile with a "real" language (C++). You can, if you wish, use fancy features like templates, the STL, classes, dynamic memory and so on. You can extend it with extra RAM, EEPROM, and port-expanders. You can use I2C, SPI, serial, 1-wire, and so on. You can connect USB and Ethernet. With a few extra chips you can have radio communications, or RS485.