I know IIS logs all requests made to the server.
If my application makes requests out to other web services, is there a way to see what the response was or at least the headers of the responses?
I know IIS logs all requests made to the server.
If my application makes requests out to other web services, is there a way to see what the response was or at least the headers of the responses?
No.
Why not? Because you're not using IIS to make the request. You're using ASP.Net or WinHTTP or your own sockets-based application. IIS is just a container for your app.
So because it doesn't make requests, "IIS" doesn't listen for responses. Your application does that. Depending on your app framework, you may be able to enable logging externally; otherwise, uSlackr's Fiddler suggestion is about it.
IIS only logs high level information for requests processed by the web server like the user's IP address, URL requested, and the status code that was returned (200,404, etc). See this website for an example of the data that gets logged. If you want to view the raw results of your code you will need to use a packet sniffer like wireshark or a debugging proxy like fiddler.