Open source programs are worldwide in use of nearly everybody who uses computers. The great idea of sharing ideas and solutions help everyone who is using that program. If you need special features and you are able to program, you can modify it to you needs and give it back to the community.
USBProg is a tiny USB and Atmel MCU based device, which can be programmed to the users needs.
Not only the hardware but the software is open source, so you build your USBProg on your own or buy it e.g. from the initiators website . With a little graphical tool you can program your USBProg to run as a ISP programmer, programmer for AVR32, a USB to Serial adapter, JTAG/ICE programmer/debugger or even a logic analyzer.
As you see: This little gadget is very capable of many different jobs and if you need something like this for a whole different project, why not program you own variant ? There are enough examples which help you to make your own variant.
As this project is still very young, some firmware versions are not completed up to now, so you should check out the website and forum at Embedded-Projects.net frequently. Additional it makes sense to have a look into the source repository at Berlios .
For my EasyAVR5 Board, I need the JTAG/ICE (mk2) firmware, which is today (May 2008) not completed, but it already works quite well with my Eclipse/WinAVR development kit together with the avarice tool to program and debug my atmega16 mcu.