I've developed a simple, Java-based IDE for writing assembly code for the ATTiny10 family. I've also developed a simple HV programming shield that works with the IDE to create a complete solution for writing code and then programming an ATTiny10 device. Since my design implements a high voltage programmer, this means you can write code that sets the RSTDISBL fuse in order to use the RESET line (pin 6 on the ATTiny10) as an additional I/O pin (PB3, ADC3, PCINT3) and still reprogram the device later. The code and hardware design is still alpha but, if you're interested in trying my IDE, check out the project page, here: https://sites.google.com/site/wayneholder/attiny-4-5-9-10-assembly-ide-and-programmer
Note: while written in Java, the IDE is currently packaged as an OSX app, so it's only available to Mac users at the moment. I'd like to release Win and Linux versions, but I need to figure out some details on how to link with the RXTX serial library on these platforms before I can do this.