Cinchona is a small village up the mountain road (hwy 126) from La Selva near the Poas Volcano . The town is known to birders primarily for a restaurant with hummingbird feeders. Much of the village was nearly destroyed in the 2009 earthquake. As of 2013, the most important locally-owned restaurant, The Hummingbird Cafe, re-opened with even more hummingbird feeders. Several species of hummingbirds are always there. It's definitely worth a stop. If you do stop, please don't forget to donate a little to the tip jar. The hummers eat a lot of food. One can also visit Poas Volcano National Park or the Waterfall Gardens close by.
The Waterfall Gardens also have a lot of of hummingbird feeders which may make it worthwhile if you need to photograph some high-elevation hummers. The Waterfall Gardens is a slick, touristy dream for Costa Rica. It's hard to spin it any other way. It's expensive for individuals who are non-residents (at least $36), but the feeders are very productive. All people are moved through a system of exhibits and natural waterfalls towards the final destination where they are picked up by bus and brought back to the entrance of the gardens. You can walk (and bird) at your leisure and there are several trail options. I managed several nice high-elevation species on the way down to my car (Prong-billed Barbet, Costa Rican Warbler, etc.) If you can stay overnight (an expensive option) or arrive very early before the tour buses get there, it may be more rewarding. A couple of other exhibits - the Butterfly Garden and the Frog Garden - are also nice attractions.
You can find many of the same hummers at the small, locally-owned "Hummingbird Cafe" down the road about 10 minutes away and it's free. The light is better though at the Waterfall Gardens if you plan on taking pictures. If you find yourself at the Waterfall Gardens for family reasons, bring binoculars and a camera, ignore the Disneyland feel to the place, and start looking for birds.