I'm in the IT/software industry and I've usually gotten interviews from applying online(monster, careerbuilder, etc.). When I was unemployed I tried to send out as many as I could (about 20 or so a day). I only did cover letters or really changed my resume for maybe a few day for ones that I was really interested in. I had to take crappy pay for a year or more before I got something decent since I didn't have experience and my field wasn't too hot when I graduated.
Networking helps a LOT. If you know anyone that works at a company that might have a position for you, you can hand him/her your resume and they could pass it along to HR. Also sometimes companies release job openings to the employees first to see if they can refer someone they know. It's definitely a whole lot more likely you'll get a call for an interview that way unless other industries are really that different.