I am feeding flightradar24.com from a Raspberry Pi and a USB SDR dongle running DUMP1090. Living near the final approach of a large (but low traffic) International Airport, I usually have an ADS-B signal to upload before a departing plane's landing gear are even retracted. There is plenty of overlapping coverage nearby for the higher altitudes that have better sky views than my receiver, but I feel it worth contributing my data to FR24 since it fills in the low-level gap in their coverage. As a benefit, FR24 gives me a free business membership just like WU does for PWS contributors.
Through DUMP1090, I discovered that I live along the "great circle route" between northern Europe and most of the USA's east coast (NYC, Washington DC, Atlanta). In the past few minutes, my receiver has tracked Air France and JIA (Japan) outbound from NYC, and WOW (Iceland) and British Airways inbound to Baltimore/Washington. At 5:00 AM, half of the planes in the air locally are FedEx and UPS flights. There have been ties when I've had three Airbus A380's on the screen at the same time, and I wonder what percentage of the entire production run that represents.
I also discovered that our airport is frequently used for touch-and-go training flights for some mysterious government airlift program that operates a small fleet of 757 and 767 jets in plain white livery. FR24 seems to filter them out on their site, but my local receiver is seeing them on ADS-B and I have collected a slew of their transponder addresses.
I'm in for well under a hundred bucks for my complete setup, and it is slightly more interesting than watching grass grow.....