Hippynerd:
Teensy Tiny Arduino Board With An ATtiny85 | Hackaday
I've been thinking about trying some of these, They are the same thing you are doing, but in a nice little package.
After you've programmed it, you cold cut off the tab and and make it even smaller.
Hmmm...looks cute but it's quite expensive for just a chip on a PCB. Plus it uses a bootloader, ick!
I just bought some of these on eBay: http://www.ebay.com/itm/190747889648
I haven't used one yet but six holes wide is just enough for a Tiny85 and a connecting wire along each side (see attached image). 4 holes long is enough for the Tiny85 and I can snip the boards to any length I want for individual projects.
The Digispark looks about 8x6 holes big - a PCB that huge would have half of it free for extra components. 
(wish my cellphone camera had a better macro...)
