Because many of your linking activities take place inside eBay, you need to play by eBay's rules on the subject. Although eBay generally doesn't mind links, it gets a little sensitive about links placed in your auction text. According to the official eBay policy on such things, you can't place a link in an auction listing that leads a customer to an off-site sale for the same item. You can, however, use off-site links that lead to more product information or customer service information. In general, you can link to anything that helps buyers complete their transactions inside eBay. You can also add a link to your About Me page, but don't go overboard -- eBay lets you put in one link of your own to the About Me page (in addition to the one eBay includes automatically at the top of your auction). You can also promote your eBay store as much as you want because eBay gets a cut of sales over there as well.

If you do any business on eBay, take the time to read and understand the linking rules. They don't take that long to work through (and they aren't terribly boring). To see the complete eBay rules and regulations on linking, visit Links Policy.