what's the domain? Every domain is associated with a primary IP address. Name servers translate www.someDomain.com into IP addresses. If you can find it via the www address, the you should be able to easily find the IP.
I just did an nslookup on Google. It returned 3 IP addresses. The first one is 126.96.36.199
So...let me type in http://188.8.131.52 into a browser...google pops right up.
Now it may be that there is no default/index document on the domain you are trying to reach, in which case you need the exact path to the document you are trying to access, say Google Advertising programs: http://184.108.40.206/ads/index.html