Great park at Bloor and Christie. In the summer there are regular minor league baseball games here. If your pro team is in last place in their division, and you are not in the mood to pay full price for a ticket and 11$ for a beer, bring a picnic out here and enjoy some low stress baseball from the hillside.
Also, Christie Pitts is a relatively uncrowded area for jogging as well. There is pay parking along Christie and Bloor, but you can usually find it for free on the north and west sides of the park.