A "larger" USB board is required to complete the Leonardo series, maybe Leonardo MEGA, based on AT90USB1287 microcontroller.
There is a neat little board coming with wifi and USB powered with linux, this may have some nice USB possibilities.
Using the Bridge library in your sketches, you can link the 32u4 to Linux, launching programs and scripts, passing them parameters (sensor readings for example) and reading their output, thus creating a strong integration between the creativity of your sketch and the power of Linux. The Yún supports Shell and Python scripts out-of-the-box but you can install a wide range of open source software and tools.
Yes, there are a lot of boards based on ARM and Linux... what I want, is a an AVR USB micocontroller, powered at 5V, with more RAM and Flash than Leonardo. Don't care if it will not have all the pins as Arduino MEGA "footprint".
1) An easy use of AT90USB1287 as I am not yet able to produce a PCB for it and my soldering skills and tools are still under SMD requirements;
2) If is produced by Arduino, it will be available also in my country at a reasonable price.
Unfortunately, I don't expect this board to be available soon (if is to be, I guess the board will not be released without Wiring language support - which I don't need it), so I will try to find solutions, including the finalization of my CNC Router...
Well, there's Arduino Due...
(Not 5V, not AVR.)
At this point, I'd hope to skip the avr USB chips and move on to XAVR for "bigger but still 8bit." But they don't do 5V either.
Sounds like you want something like Teensy++ 2.0 ?
Full disclosure: I'm the creator of the Teensy boards, so my opinion is probably biased....
Agree with the OP, I'd love a Leonardo with more I/O pins, without having to faff about with charlieplexing or shift registers. The Mega is a bit overkill, but somewhere between that size and the current size would be great. (But I'll take what I can get!)
That said, the Teensy++ looks very intriguing! Paul, can that use the same mouse and keyboard libraries that the Leonardo does? (keyboard.begin, et al)