The number of DXpeditions with web pages has grown very large now, and I just don't have the time to properly maintain such a large list, but I will provide info here to take you to the best sources of DXpedition info that I know.
As with anything you are looking for on the Internet, a Bing search is the best way to find it. You can simply type the callsign of a DXpedition station into the Bing search box below and if the DXpedition has a web site, Bing will find it. Another idea is to type in something like "san andres dxpedition" if you know of a past, present, or future trip to San Andres, but you don't know the callsign.
One person who seems to have enough time to keep a large page of DXpedition info constantly updated is NG3K. His Announced DX Operations page is excellent.