There is something like that, and I'm sure someone will post a link. I do caution the use of it... All of the tools I have seen have been out of date and innacurate for some routes.
Basically... this is how we work. Busses, Monorails, and Watercraft run from the Disney Resorts to/from the Disney Theme Parks, Water Parks, and Downtown Disney.
To travel from Resort to Resort, you must transfer at a Hub (Theme park or DTD). Some connections can be made quicker than others by the use of better transfer points.
The best place to transfer is a place closest to where you are, or where you are going.
For example, if you're going from Caribbean Beach to the Contemporary, you'll have two options. CBR is located very close to the Studios... and CR is located very close to the MK. You can use either for transfer points. The first is to take the bus to the Disney-MGM Studios, and catch the Contemporary bus from there. The second is to take the bus to the MK, and either walk or take the Monorail to the Contemporary.
Epcot should not be used as a transfer point for the Swan, Dolphin, Yacht, Beach, or Boardwalk. Use the Studios instead, and connect via Watercraft.
DAK closes early, however, it makes a good transfer point for AK Lodge.
MK is a good transfer point for Contemporary, Polynesian, Grand Floridian, Wilderness Lodge, and Fort Wilderness. The first three connect via Monorail, the last two connect via Watercraft.
Downtown Disney can be used for late night connections, once parks start to close. Although additional busses are put up on route to compensate for crowds, it should be noted that DTD can get congested during peak dinner times, when everyone else is doing the same thing as you.
The best advice I can give you... when you're confused, find someone in PURPLE... and ask them. Never rely on transportation information from Non-Transportation people. They have no clue what they're talking about. Always make sure to ask a Bus Driver... we're always more than happy to help you out in any way possible, and advise you on the best route at the current time.