Oak Hill Park Splash Pad, St. Louis Park
Rhode Island & 34th St
By far the best free splash pad in the Twin Cities (that I've been to, at least). It has a number of water elements; the largest I have found so far. It also has good playgrounds (one for older kids as well as a toddler playground) and restrooms inside the park building.
Manor Park, Robbinsdale
Lowry & Abbott Ave, behind North Memorial Hospital
A nice little splash pad with several water elements that are staggered in operation. A nice little playground and tennis court are also located there.
North Mississippi Regional Park, Minneapolis
53rd N & E Lyndale
Water sprays out of a large "boulder" in the middle of a wading pool. The park also has many trails, a nature center, plenty of picnicking areas and indoor restrooms.
Cleveland Park, Minneapolis
Just off Lowry at Queen, behind Lucy Laney Craft School
A zero-entry wading pool with a few elements in the pool. My kids like to be able to "swim" while playing in the water.
Bohanon Park, Minneapolis
49th Ave & Bryant Ave N
A wading pool with three pipes sticking up int he middle that spray water in various manners.