Yes, these beacons are known as PiFER's, or pirate beacons.
Here's a small, frequently changing list: http://www.hfunderground.com/wiki/High_Frequency_Beacon
They provide a service:
- DX window openings on a variety of frequencies.
- Areas of maximum propagation.
- Skip distance.
They provide entertainment:
- How many can you log?
- Discover the best time for these beacons.
- Can you find new ones no one's heard of?
- Is it a PiFER, or a commercial/military beacon?
IME, you're addicted, or you're not. If you spend many a winter night DX'ing longwave areo/marine NDB's, if you go "YAHOOO!" at a power outage and turn on the portable SW radio, you'll have a blast with the PiFER beacons
* PHFER and PiFER are interchangeable.... those of us running a "Part 15" (RSS 210 - Canada), often refer to them as PiFER