[GandalfDir]

To summarise and add:

Here are the benefits:

1) Commercial
- You earn money by advertising.

2) Traffic
- you generate traffic for your main site

3) Links Popularity
- you build links popularity for your main site

4) PageRank
- as a rule directories provide static pages and Google loves them and gives pagerank for some unkown reason.

5) Search results
- another tendency is that directories win higher placement in search results. If the word is not very popular.

Finally, my own directory is good for resources purpose. We have built it to spesifically meet our resources needs. Due to industry spesifics we cannot make everything for client and so useful links do help.