In general - no - but with a few exceptions!
The web is unfortunately littered with "directories" offering you the chance to be included for only $9.99 as a one off fee - sometimes even more! Be cautious about throwing your money around - there are a lot of so called directories out there that are not much more than web pages which will include a link to your site for a fee. Many of these sites have very low traffic or are poorly constructed meaning that your inclusion on them will do little if anything at all to boost your sites performance.
Specialist Directories / Niche Markets
There are however exceptions. If you work within a very definate market niche there are often specialist directories that do get a fair amount of traffic and sometimes act as a gateway for people searching for services. An example might be if you are a counsellor - there are a number of counselling directories which get a fair amount of traffic some of which charge a fee. Paying for inclusion may well result in a return on your investment.
The Yahoo Directory
The Yahoo directory is another directory where it may be worth considering payment. At $299 a year however inclusion is not cheap and so you need to consider what advantage your inclusion might bring. The good news though is that if you are a non commercial organisation inclusion is free via the "standard submission" option - but this means that it can take a while to get your site reviewed and included.
What to look for in a directory
Put yourself in the position of someone doing a search for the services you offer. How professional does the directory look, how comprehensive is it and how easy is it to navigate? Would you find this directory useful? You also need to consider how relevant the directory is to what you do - if the content is either directly or indirectly relevant to what your organisation does then maybe it might be worth considering.
Page Rank (PR) (discussed elsewhere on this site) is another factor to look at. Page rank is a rough indication of how useful Google sees each page on the web. You can easily view a web page's PR by downloading the Google Toolbar and looking at the Page Rank bar. Sites with a high page rank are worth considering - for example the international Yahoo Directory and DMOZ both have a page rank of 8 whereas many others only have a PR of 1 or 2. The higher the PR the better - generally if a directory is not relevant to your profession or specific to the services you offer directories with a low page rank are unlikely to offer much if you are included.
Don't just sign up to a Directory and then forget it!
(Although if you've paid a one off fee for inclusion in a directory then maybe you can!)
For directories where there is an ongoing annual or monthly payment required it's important to monitor how well the directory is performing for you. You can do this by setting your site up with a good web analytics package - such as Google Analytics. Within your Analytics package the two most important things to monitor are:
i) how many people are finding your site via your inclusion in the directory?
ii) what do these people actually do when they get to my site? Set "goals" on your site and monitor how many people being driven to your site via the directory go on to perform these. A goal might be a visitor buying something from you, sending an email, making a donation or whatever you want them to do. You also need to monitor bounce rates - if 98% of visitors coming to you from a directory link bounce (ie they look at one page they land on then leave your site) this isn't a great sign either!
iii) consider your ROI (return on investment). If hypotheticaly only 1 in a 1000 people that find their way to you via a directory go on to buy anything from your site and it costs say £50 a month to appear in the directory your initial reaction might be to not bother! If however you are selling cars or other high value items with a good markup then it may well be worth continuing to advertise! As for any form of paid for online advertising its important to keep records so that you can continually review whether your marketing strategies are paying for themselves!
