1. VerilogHDL vs. VHDL For the First Time User Short introduction to HDL w/ observations about two popular HDL's.
2. The Verilog HDL Language Reference Manual (PDF format) copyright 1991 by OVI. 296 pages of language definition and reference. Quite technical, a complete reference, but superceded by the IEEE Verilog standard.
3. Verilog Tutorial 238 page tutorial by Deepak Kumar Tala
4. http://www.eg.bucknell.edu/~cs320/1995-fall/verilog-manual.html A link to a simplified Verilog manual
5. http://www.ee.ed.ac.uk/~gerard/Teach/Verilog/index.html An intro to digital design and Verilog
6. http://www.asic-world.com/verilog/index.html Tutorial, examples, tools, books, links and a comprehensive FAQ
7. http://bawankule.com/verilogfaq/ Lots of info here: FAQs, resources, examples and links
8. http://www.eg.bucknell.edu/~cs320/fall-1997/verilog.html A link to Verilog resources at Bucknell University
9. http://dmoz.org/Science/Technology/Electronics/Design/Hardware_Description_Languages/Verilog/ A dmoz search, with many usable links
10. http://www.simucad.com/ Silos is a widely used Verilog simulator. They have a good demo about it.