This is an active area of research. There have been attempts at creating usable security tools and lots of userstudiesuser studies of existing tools (typically with critical results).
A good anthology for work in this areasarea (a few years old now) is Security and Usability edited by Lorrie Cranor and Simson Garfinkel.
There is also a workshop every year called Symposium on Usable Privacy and Security (SOUPS) with lots of papers. However the best usable security papers tend to appear at the top security conferences (Oakland, Usenix Security, and CCS).