I'm a huge proponent of submitting yourself to directories that are directly related to your business. Playing in your own neighborhood is an important part of directory and linkbuilding research.
There are a few directories I don't think we can afford NOT to be in, for various reasons. Some provide great links, some listings rank really well and help with saturation. Some even drive a lot of good traffic. It's important to think of directories as more than just a link – they're worth looking at from a few different angles.
Considering directories from the three angles outlined above, here's my list of MUST haves:
You are almost always going to get a Google Back Link from the Yahoo Directory. The cost is around $299 to submit and a recurring $299 that is auto-charged to the original card you submit with. I've seen one listing result in multiple backlinks because you're also added to the overseas directories. I do see Yahoo Directory listings show up in search results, so having a nice profile here will help you with search engine results saturation.
You can probably call me biased, but I really like the folks at Best of The Web. I list most of my clients in this directory and with their local directory and quite a few with the big directory at BOTW.org. I've had a few minor glitches, and I found their customer service responsive and helpful. Pricing is competitive: a listing in the local directory runs about $10 a month, and in the main directory for $99.95 per year or $249.95 for a lifetime listing. If you have the money to spend, I recommend the lifetime listing.
If you offer a service or product-based business, writing a guide at Work.com can really get you some nice exposure. Although some of their links are followed, I haven't seen anyone receive Google backlinks from Work.com. I do think this is a great place for establishing your expertise and you can write and optimize your guide to rank well for a variety of search terms. It's definitely worth the time investment.
This is a human-edited directory that is REALLY picky if you want a free listing. I suggest spending the $40 for an expedited JoeAnt review. They will tweak and change your listing to fit their stringent guidelines. This site is nice for a backlink and also has themed categories, which makes the link and the links around it relative to what your site is about.
Squidoo is an AWESOME site for search engine results saturation. If you have a Squidoo lens, you're going to see that lens rank nicely for your brand name and even some low-competition keyword phrases. The key to results saturation is controlling as many listings on the search page as you can via your own site, directories, forums, social networking profiles, etc. The more positions you take on a page, the less your competitors control – that means more real estate for you!
I've written before about how I'm not a huge fan of the Yellowpages.com type websites. I find them to be difficult to navigate and their "SEO sales" tactics leave a lot to be desired. That being said, a free listing at YellowPages.com can generate some nice results saturation and decent traffic, if your business is truly dependent upon the work-nearby or walk-in crowd.
I see MerchantCircle rank near the top of most queries I perform. I think you should definitely have a listing here. They offer a few models and variations on their submission, but the free directory listing is enough to show up in the search results for your brand name. Some clients seem to gain MerchantCircle.com listings via other services they use to push their data out to other websites. Either way, it is valuable and worth your time to be sure you're listed.
It's a valuable listing – if you can get it. Right now, I think the wait time is at least 6 months. So submit yourself for free and wait. I haven't found that submitting again and again helps at all, so just submit once and move on. One day you'll check your backlinks and, lo and behold, you might just see a DMOZ link in there.
This directory has come on and off of my recommended list a few times. Right now I do think a Business.com listing (not PPC ad) can help you with search engine results saturation. The links are all passed through redirects, so there's no link benefit from this listing. This one is at the end of my list because its value is questionable, and at $299 it is a bit expensive for limited traffic.
Overall having all of these listings might be a good investment. As a small business owner, being aware and chipping away at the list by submitting to one a month or one a quarter is okay. You do what you can with what you have. I'd try to do as many of the free listings as soon as possible, if you already haven't. The longer the listings and links "marinate," the more benefit you will see.