Have a look at these books:
1. PSL (http://www.noveldv.com, www.abv-psl.org)
2. SVA Handbook (**broken link removed**)
3. Assertion based design by Harry Foster et. al.
I also wrote a PSL tutorial for Veri-page, http:://www.project-veripage.com
The links in #1 & #2 contain a large set of example code that you can download and start using!!