So you are desperate for getting some PR link juice from others and are seeking the right service which would submit your site to 1000s of link directories, presumably because one SEO Guru has told you that this is the quickest and easiest way to get a huge pagerank? Before you jump on boards, wait! You are going to make some major mistakes.
1. Don't Expect Any Traffic From Link Directories: Too many times I find seo gurus advising newbies to submit their sites to 1000s of link directories in order to get a lot of traffic from search engines as well as a high pagerank. First of all, you rarely get any considerable amount of traffic from link directories. If you want to get PR juice as well as traffic, then your correct destination should be article directories, instead of link directories. Secondly, submitting to thousands of link directories is fine, as long as you follow some rules.
2. Don't Use Automated Softwares: In my bum marketing report, I wrote that when submitting your site to link directories, you should do it manually or outsource someone rather than using software. Most automated softwares list invalid URLs whose pagerank has dropped or is about to drop. Secondly, from my experience, I have found that these softwares mostly list sites that require you to give them a reciprocal link. While reciprocal links are fine, one-way links are what you should be aiming at as Google gives more value to one-way links than others.
3. Relevancy is the key. When it comes to link directories, it is NOT always a number's game: In my bum marketing report, I also advised that you should submit your site only to directories that are relevant to your content. Don't submit to a directory dealing exclusively with pets if your site is about self improvement. This is sound commonsense I know, but a lot of people make this silly mistake of submitting their sites to all directories and sundry, in the hope of getting a higher pagerank. Remember that Google rewards relevancy more than the number of backlinks your site gets. In my opinion, it is any day better to submit to 50 relevant directories rather than submitting my site to 1000s of directories whose content doesn't even remotely match mine. Don't get surprised if after submitting to thousands of link directories, your pagerank is actually dropped. That is how Google punishes untoward and dishonest people. :D
4. Be A Good Guy: You know that honesty is the best policy; well, when it comes to Google, it is better to deal with it honestly rather than trying to screw it. So, if you are submitting to say, 500 directories, it is fine as long as you don't submit your site to all of them at once. Instead, spread out your submission. Make it a point to submit your website to say, 10 or 20 directories per day, and try to be consistent. That way you will come across as an honest person rather than a fly-by-night marketer :)
5. DON'T Buy Links: Google has been cracking down on paid links of late. So even if you buy 7 PR8 backlinks, you may not get their benefit because from what I have heard from some experts, Google is actually blocking the high pagerank sites from passing on their link juice to others. For Google, pagerank is not a thing to be sold; it is a prize to be earned by hard work.
So there you have it: if you ever want to submit your site to link directories, just play by the rules and you will be OK.