AT90USB162 is the easiest way to add USB functionality to your next device, Atmel provide free open source HID (mouse, keyboard) and CDC (USB-to-RS232) code and on top of this AT90USB162 cost is same as ATMega16, so what you are waitng for?
AVR-USB-162 board provide the basic circuit necessary to work with AT90USB162 - USB connector and circuit, external power supply if your circuit require more power than 100mA which usually USB port provide, button, status LED, reset button. All AT90USB162 come from Atmel pre-programmed with bootloader which allow code to be programmed inside the chip without any external programmer, just download the FLIP software from Atmel web site and load your HEX code inside AT90USB162. To enter the bootloader mode you shoud press and hold BUT button, then press and release RST button. If you preffer to use ICSP programmer note that only AVR-ISP-MK2 is supporting AT90USB162 as there are pretty new devices, probably AVR Dude will add support later, but for the moment you can't use AVR-PG1 or AVR-PG2 for ICSP programming, another bad news is that AT90USB162 supports only debug Wire not JTAG so to debug it you should have the expensive AT-JTAGICE-MK2.
AT90USB162 microcontroller with 16KB Flash, 512B RAM, 512B EEPROM
ICSP 5x2 pin connector for in-circuit programming with AVR-ISP-MK2 (you generally don't need to use ICSP as you can program via USB)
Debug Wire could be performed by 3 wires connected to ICSP (AT-JTAGICE-MK2 have such lose wire connector which to be used, you need VCC, GND, RST signals only)
USB 2.0 Full speed connector
User button BUT (can be used to enter bootloader mode after reset)
Reset button RST
Takes power from USB no need for external adapter
External power supply and voltage regulator if USB can't provide enough power
Quartz crystal oscillator circuit 8Mhz
Extension pin headers for each uC pin
Four mounting holes 3.3 mm (0.13")
Grid 100 mils
FR-4, 1.5 mm (0,062"), green soldermask, white silkscreen component print