eBird is a revolutionary citizen science website that allows any and all birders of all skill levels to submit locality and abundance data about the world's birds. Whether you are birding in your garden or the most remote jungles of Africa, your data become publicly available for worldwide research.
The website has lots of built in functions, including viewing birding hotspots, seeing species' distributions, and even viewing summaries for regions' birdlife.
Data are constantly reviewed for quality, and observations of rare birds are often "flagged" to let the user (and the reviewer) know that an unusual bird is being reported. Hundreds of volunteer reviewers parse these data and help sort out which records are legitimate, which are misidentifications, and which are genuine data entry errors.
I presently review data primarily in Central and Southern Africa, and frequently use eBird data for my research.