A "Link to Us" page can provide an automated way of getting incoming links to your site. What we are talking about here is in effect a reciprocal link exchange page. What is reciprocal linking? A reciprocal link is essentially a bribe. It's perfectly legal, morally correct, and in fact, it's how the Internet was meant to be structured. A Reciprocal link is where two webmasters or web site owners exchange links. Web Master A puts a link from their Site to Web Master B. Web Master B puts a link from her site to Web Master A. It's a Link "Exchange." In terms of how this shows your 'importance' to search engine spiders and software, the more incoming links you have, obviously the more important others perceive your website to be, therefore the search engines will think the same. Its one way they have of determining that your site is still live, still active and still of interest. That means, you will rank more highly. With almost 25% of the worlds websites redundant at any one time, this is one of many ways, search engines determine how important you are to others on the web.
When a clever Web Master finds your site and they see and that you are trading links with other web masters, they are very likely to contact you immediately and request an exchange. This means you are likely to see more requests for a link exchange than you are likely to see people linking to your site because of your "Link to Us" page. Most web masters will not even bother trying to exchange links with a site than doesn't already have a quality links page. It's all about the numbers. You can get more links faster if you have a quality link exchange page.
There are some instances where it's not appropriate for you to link off your site. If you're an educational site, a non-profit site, a charity site - you are probably mandated not to exchange links with commercial entities. But, if you can quickly acquire incoming links by trading links with other web masters -by all means do it.
Are there any down-sides to Trading Links? Not really. But, it will take time. Meaning, every time you get a Link Exchange Request, you need to actually publish the link to the Web Master's site that your trading with to your Links Page. The biggest problem is that you need to have a Link Exchange Page that benefits the Web Masters exchanging links with you. Meaning - it has to have a decent Google Page Rank. So, when you're starting your site, make sure that your site structure includes a page for trading links.
You also want your links page to inherit some of your site's Google Page Rank, so make sure that you get that page crawled and indexed. In fact, your main links page should have a link directly from the home page. Some Webmasters try to bury their links pages inside their site. They think they're not "giving up" valuable page rank that way, but what they're really giving up is valuable link partners who won't trade links with them because they have buried their links page..
Finally, as with your "Link To Us" page, make sure that you are controlling how the other web masters are linking to you. You can go so far as to provide the HTML code of the link that you want them to use right on your Link Exchange Page. Reciprocal linking is the basis for the web. Such linking creates the structure of the Internet. Not only can it provide a powerful tool for Search Engine Optimisation, it can also provide qualified traffic if the sites that link to you have a genuine interest in your site's industry.