Making a custom web directory

[Jbeaty]

I am wondering if it is beneficial to launch a social bookmarking website based on Semantic Scuttle [http://semanticscuttle.sourceforge.net/demo] in order to gain inbound links. For the sake of example, say my industry is ebooks. I would of course add links to all of my products to the site. In addition, I would want to add links to competitors products to the site to make the site actually useful and not look like spam. On the face of it, is this a good idea?

Secondly, I of course wouldn't want to be helping out competitors, so would any of these actions be advisable?

1. add nofollow links to all links except those pointing to my site.
2. ads or featured listings pointing to my links.
3. I make it so only voted on links are dofollow. Thus, competitors could actually get links from my site. Naturally, I would vote on all my submissions.

The idea of the site would actually be to provide a meaningful service. Once it's done I would want to get people linking to it.

Any advice? Thanks!

Edit: I added scenario #3 which I think is probably the best option, if this is even a good idea. I would also make some static content to really make this a good resource!

[Jbeaty]

One more idea is if I write some code that says if a link on my site gains more than say 3 votes that it turns into a dofollow. Again, I plan on submitting links to competitors sites for any ebook I can find, so it sould actually be a helpful resource.

[EGOL]

Google is usually quick to identify methods of manufacturing links.