I am looking for an UCI compatible engine with an ELO of less than 1800. Not a version of Houdini or Stockfish with an ELO of 1800. I want a engine with a real ELO rating of 1800 or less. If you can help me with links, that would be great.
Take a look at numpty. It claims to have a ELO of about 1500-1800. I've played it on FICS before and it usually has a blitz rating of 1900-2100. Note that FICS ratings are usually horribly skewed by all the cheating that happens on there.
Adam Hair has a rating list for weaker engines:
Grizzly and Chenard are UCI, but a lot of the weaker engines tend to be CECP.
Actually, on the CCRL 40/4 there're around 170 engines under 1800, not just a dozen. You can also check this list based on bullet games: http://e4e6.com/ratings.php?id=1001 Most of the engines work properly, especially at long time controls. Almost all of them are still available on the Internet, just Google them.
There is an engine called Delfi made by msb software. It is designed to play at lower ratings but also to play more like a human amateur. It is commercial, not free but I think there is a free version with some limitations.