Hammocks are wonderful, portable, outdoor couches. They can be bought for as little as $15 at outdoors stores. A good hammock spot is often sunny, with smaller, sturdy trees about 8-10 feet apart, set back a bit from a path so people don't bother you too much.
Frosh Quad
The trees and the fence at the western edge of the quad, near the grills, are perfectly spaced for a hammock. Probably the most consistently sunny spot, especially in the afternoon.
Mission Park
There are a number of trees near the Haystack Monument (especially on the Dodd side) that are suitable. Sometimes a bit shady for early- or late-season hammocking.
Sawyer Lawn
A few trees can be made to work over by the Congregational Church. The trees are a little too thick, and it loses sun in the afternoon.
Dodd Quad
There is a tree on the Lehman side of teh Dodd Quad that will take a hammock set up within its branches, instead of between two trees.