I was wondering if DotNetNuke provides a way where i can extend the site settings? I wish to have some custom settings for each site .I cannot use web.config file as it is shared by all the sites

You could. But I'm not sure that would be a recommended practice. It might be better to create your own class mySiteSettings, for example, that inherits from the class that stores the site settings ... or any other class.

I'm not sure how you intend to use this, so it's difficult to say if this is a good idea, or if you should provide something else that lets you store other "settings." Perhaps you could explain your use case in more detail.

The scenario is as follows. I have multiple sites within my DNN instance. Now for each site i want to specify a 3rd party shopping url specific for that site. eg: site#1 : www.shopsite1.com site#2 : www.shopsite2.com etc etc Now in a normal application i would have a value called "SHOPURL" under the in the web.config site. However i cannot do the same here as the web.config is shared by all sites. I am comtemplating creating a table within DNN database which has portalId & shopURL as columns and use that to find out appropriate shopURL specific for a site. I was just hoping if there was an easier solution

Thanks.

I found a discussion similar to this one in the DotNetNuke forums.  Look here.

My interpretation is that the mechanism for creating and using custom portal settings does exist.  You will just need to provide the UI for setting and getting them.