An addictive home-valuation site. Check the "zestimate" of your existing property and / or one your interested in buying. The site also lists the final price of similar homes that recently sold in the area.
Southeast Wisconsin's Multiple Listing Service (non-professional)
Another fun site for house hunters listing local properties for sale and their corresponding taxes, amenities, square footage and more of. Be careful though, because this public listing is not updated as frequently as the listing service an agent would have access too.
Terapak Realty & Management
Norm Terapak has a long history of being a fair, local agent.
Milwaukee Journal Sentinel Online - Homes
The Milwaukee Journal Sentinel's comprehensive home listing database.