The Windows SharePoint Services (WSS) object model contains a SPWeb class that is used to obtain data about and perform actions on WSS websites. SPWeb has a couple of methods that allow you to get at files stored in sites: GetFile(string url) and GetFileAsString(string url).

What the WSS SDK does NOT tell you is that you don't need an instance of SPWeb for the specific WSS website that contains the file you are looking for to use those methods. In other words, if you have a file stored under a site named "Human Resources", you can use a SPWeb instance for a site named "Manufacturing" and still get the file under Human Resources:

//get the site server
SPSite server = new SPSite("http://MyWSSServer");
   
//get the Manufacturing web
SPWeb manufacturingWeb = server.AllWebs["Manufacturing"];

//url to the Human Resources file
string hrUrl = "http://MyWSSServer/HumanResources/doc.xml";

//get the HR file using the Manufacturing web
string fileData = manufacturingWeb.GetFileAsString(hrUrl);

GetFileAsString() is NOT a static method, which would have explained (sort of) why this works.

The good thing about this is that you can get files anywhere on the server and you only need to obtain the root web (or in SPS, one of the System Areas) to get at files. Webs deeper within the site structure are more difficult to obtain, especially in SPS, and this little quirk about the SPWeb class will make it easier to get at files in those sites.