We spent the weekend camping along the Snake River about 30 miles south of Boise at a BLM campground called Swan Falls (http://www.blm.gov/id/st/en/prog/blm_special_areas/birds_of_prey_nca/recreation/swan_falls.html). Just a great place to spend the day or two camping, hiking, fishing or bird watching. Swan Falls sits along the southern edge of the Snake River Birds of Prey Conservation Area (http://www.blm.gov/id/st/en/prog/blm_special_areas/birds_of_prey_nca.htm), so if you enjoy bird watching this is the place to go. Like the name implies, the Birds of Prey area is full of hawks, eagles, owls and other raptors. Had a hard time falling asleep due to the owls hooting and then hearing the hoots echo through the canyon. Woke up early to the sounds of geese, chukars and other assorted bird calls.
For camping there are several places to boondock along the river and there are 2-3 outdoor pit toilets available for use. The road down to Swan Falls is a little steep, so check your brakes before you head down to the canyon. Campgrounds are off a well traveled dirt road.
Another site to see is the Swan Falls power plant, built in 1915 to supply power to the silver mines further south in the Owyhee Montains. If you like to fish there are some boat launches in the area as well.
Overall a great place to make a great day or two side trip if you are in the Boise Idaho area.