The good thing about flipdog is that it actually takes you to the job announcement on the web site of the company that is looking for someone.
The bad thing about all of these sites though is that I haven't gotten many bites by potential employers when I applied for positions directly, or by having my resume available on their (monster, hotjobs) web sites. I'm on the US east coast and have ASIC/FPGA experience. Last fall myself, and several others that I know, tried using the web based approach. The results were pretty dismal for all of us. I imagine when the economy is doing well, these sites may be useful. But when things are slow, as they have been in this area for the last two years, I've yet to talk to anyone that's gotten a decent job lead through one of these services.
The best approach that I've found is networking. Get your resume into the hands of people that you know inside a company. Talk to people that you know about which company might have job openings. Another good source of info are product reps. These guys that are trying to sell you stuff are probably also dealing with other companies in your area that are in the same or similar business as yours. These guys have a pretty good feel for which companies are doing well and of course they have the names of people within the companies that you can contact.