I have not heard of that website, but being from Michigan myself, I have been on the search for some trout streams.
One website I've been frequenting is Michigan Rivers and Streams
They give you info about the area, current weather conditions, and links to driving directions, USGS stream data, local fly shops, etc. They also have a nice table showing what's hatching for each month for that area.
Their maps feature doesn't seem to be working for most places, but they give you the name of the river and area it is in. With that info, you can easily get a Google map of it, or use the USGS site they link to to see maps of the area and more precise location (GPS coords, quartering method, etc).
Best of all...it's free
The Manistee is the river I'm most interested in lately, but I'd like to try out the Au Sable once I get more into the sport (I'm just starting out fly fishing).