This answer is both simple and complex.

Simple because there is SERIOUS money changing hands at eBay, and they will pay you a commission for referring people to their site.

Did you know eBay is the larget online retailer in the world? Not only are they the largest retailer, they also have the larget customer base. A customer base that spent over $50 Billion in 2006.

Here are the highest worldwide annualized gross merchandise volume categories for eBay.

eBay Motors at $16.5 billion
Consumer Electronics : $4.9 billion
Clothing & Accessories : $4.5 billion
Computers : $4 billion
Home & Garden : $3.6 billion
Books/Music/Movies : $3.1 billion
Collectibles : $2.7 billion
Sports : $2.6 billion
Business & Industrial : $2.2 billion
Toys : $2.1 billion
Jewelry & Watches : $2 billion
Cameras & Photo : $1.5 billion
Antiques & Art : $1.4 billion
Coins & Stamps : 1.3 billion

You do not have to be a rocket scientist to see the profit potential at eBay.

Now lets look at the complex part of 'Why eBay'.

It is Complex because figuring out how to get your cut of the eBay profits can be a challange. People do not like to be pushed into doing anything. That rules out email marketing for eBay profits. The single best way is to entice your site visitors by displaying small ads on your website. Look at all of the sites with Google Adsense ads ... it hard to reach a site these days that does not have Google ads displayed.

Auction Ad Blocks creates a very attractive ad for your site, an ad that looks alot like the Google Adsense ads. The only difference is you are displaying eBay auction items and not contextual ads. Plus, with Auction Ad Blocks you control what products are displayed on your site so you can easily connect your site content with relavent eBay auction items.