There are a number of places to visit outside Iquitos [1], though frankly the surrounding jungle is far more interesting.
About 15 minutes west of the city is the Quistococha Tourist Center (8 a.m.–5 p.m. daily), which has a lake with rowboats, a fish farm, and a small zoo. Iquiteños head here and to Lago Moronacocha, three kilometers east of the city, on the weekends to swim, sunbathe, and water-ski. There are a few bars at Moronacocha that offer bathroom services for guests.
Santo Tomás is a lakeside village 15 km northeast of Iquitos [1] known for carved root and ceramics handicrafts.
Links:
[1] http://www.moon.com/destinations/peru/the-amazon/iquitos