Like to run in races? The Telethon marathon, "Walk of Life," lets you have fun AND contribute to their good cause (the latter sounds good to me, the former sounds nuts, but to each his own...)...More...
The "Walk of Life" marathon is throughout eight major Italian cities, but this 10 km race in Milan will take place on the 6th of May, starting at 10 A.M. at the Piazza del Cannone/Viale G. Gadio.
There is a modest sign-up fee. Inscription--you'll need a doctor's certificate, of course--can be done from the 5th to the 6th of May, or online...sigh...only in Italian: http://www.walkoflife.it/citta_milano.aspx
Have absolutely no intention of running? Donate anyway.
Just want to avoid those areas of town that will be blocked for the runners? See the website, there's a map.
Let's hope they have better luck with the weather than the last recent marathon!