The affiliate network TradeDoubler has emailed their affiliates to ask them to help categorise their websites. Affiliates will say what type of site they run so that TradeDoubler's auto-targeting systems can better target users on those sites.
Sounds look a good idea but behavioural targeting is hugely unpopular so this is a PR risk by the network. This may also annoy affiliates a little as it'll increase the chances of people blocking/refusing TradeDoubler cookies.
Their email said;
The categorisation of websites will also enable the future launch of interest based advertising. With interest based advertising a publisher can show ads targeted to each user. The selection is based upon an interest profile built up when a user is browsing sites within TradeDoubler's network. For example, a person visiting more sports websites than average will be shown more ads related to sports.
What are the next steps?
We will be asking you to categorise your current websites when you next log in. This should only take a few minutes. You can select up to four top level categories per site and you should select the most accurate categories to match the content of your website. After you have categorised your website using the popup you can edit these categories from the “Site information” page in your account.
TradeDoubler, like Google, are trying hard not to call this behavioural targeting and are calling this "interest based targeting" instead. You can read more of the network's policy and OPT OUT of the targeting from this legal page here.