Here is a sampling of Citizen Science projects.  Some of these projects you can participate in by collecting information from your own yard.  You can also view the list as a PDF file (includes more detail):  CLC Citizen Scientist.  Some of the projects are based here in the Chicago area and others are national or worldwide.

The projects listed below cover a number of different science disciplines: insects Entomology, butterflies Lepidopterology, herps (amphibians and reptiles) Herpetology, birds Ornithology, plants Botany, and more.

2017 Project Updates
Bumble Bee Watch has announced an iPhone app for reporting sightings.
See the app and more information here

Category Project Area Sponsors
Bees BeeSpotter USA (IL, MO, OH) University of Illinois at Urbana-Chamapaign
Bees Bumble Bee Watch Canada, USA Xerces Society (lead)
Butterflies Illinois Butterfly Monitoring Network Chicago Illinois Butterfly Monitoring Network
Butterflies eButterfly USA, Canada University of Ottawa, Oregon State University, Vermont Center for Ecostudies
Butterflies Monarch Parasites Canada, USA University of Georgia
Butterflies Monarch Larva Monitoring Project Canada, USA University of Minnesota
Butterflies Monarch Watch Canada, USA University of Kansas
Insects Ill. Odonate Survey Chicago Chgo Academy of Sciences, Peggy Notabaert, UIC
Insects School of Ants Various Field Museum and others
Insects BugGuide USA, Canada Iowa State University
Insects Cicada Watch: Brood II[7] Northeastern America National Geographic Society
Insects Odonata Central North America
Insects Xerces: Dragonfly Pond Watch Project Xerces
Insects Xerces: Migratory Dragonfly Partnership Xerces
Birds Birds Citizen Science Chicago Field Museum
Birds Audubon Christmas Bird Count Western Hemisphere National Audubon Society
Birds BirdSleuth K-12[note 2] USA Cornell Lab of Ornithology
Birds Celebrate Urban Birds USA Cornell Lab of Ornithology
Birds ebird Worldwide Cornell Lab of Ornithology, National Audubon Society
Birds Great Backyard Bird Count Worldwide National Audubon Society, Cornell Lab of Ornithology
Birds Hummingbird Migration Tracker USA Birdfeeders.com
Birds Hummingbirds at Home USA National Audubon Society
Birds NestWatch Americas Cornell Lab of Ornithology
Birds North American Bird Phenology Program [9] North America United States Geological Survey
Birds What Do Birds Eat? United States University of Delaware
Herps Calling Frog Survey Chicago Chgo Academy of Sciences,Peggy Notagaert, UIC
Herps Amphibian Migrations and Road Crossings New York, USA Department of Environmental Conservation, NY, USA
Herps FrogWatch USATM USA Association of Zoos and Aquariums
Herps Herpetological Education and Research Project North America HERP Board of Trustees
Herps Michigan Herp Atlas Project USA (MI) Michigan Department of Natural Resources
Herps North American Field Herping Association North America North American field herping community
Urban Wildlife Project Squirrel Chicago Chgo Academy of Sciences, Peggy Notabaert, UIC
Urban Wildlife Chicago Wildlife Watch Chicago Lincoln Park Zoo
Plants Collection Connection: MicroPlants Chicago Field Museum
Plants Plants of Concern Chicago Region Chicago Botanic Garden and Others
Plants Nature’s Notebook USA USA National Phenology Network
Plants Project Budburst USA National Ecological Observatory Network, National Science Foundation
Invasive plants Early Detection & Distribution Mapping System USA, Canada University of GeorgiaCenter for Invasive Species and Ecosystem Health.
Conservation Habitat Network [5] North America [The Nature Conservancy and the Cornell Lab of Ornithology]]
Ecology Ecological Stewardship Chicago Field Museum
Light Pollution Globe at Night Worldwide National Optical Astronomy Observatory, CADIAS, International Dark-Sky Association
General Chicago Region Monitoring Chicago Field Museum
General Biodiversity Heritage Library Flickr images Worldwide Biodiversity Heritage Library
General iNaturalist Worldwide California Academy of Sciences
General Notes from Nature Worldwide Zooniversecollaboration
Other Geo Wiki Worldwide IIASA