I use .072 for cranks, and .092 for swimbaits.
I get them at:
http://www.luremaking.com/catalogue/catalogue-index/catalogue-items/eye_screws.htm
There are lots of other online suppliers.
Google .072 stainless steel screw eyes, and they'll come up.
My most challenging so far has been a small crank. It measured 1cm from lip to tail. I don't know how it would have swam, last it was seen was when it shot out my hand trying to do some touch ups with my dremel. I haven't been able to find it since.