KneeTheCap: Those "obscure" simulator / tycoon games are usually the best, so if you have anything in mind, please let me know.
Street cleaning simulator is not only mildly obscure, it has also an impressive 9.1 score from users on Gamespot!
As you said that you were interested in economics sim games here are a few others that you might be interested in:
East India company. By no means a flawless game, but it is fun. You basically run an East India trading company. Like many Paradox released games, it is a bit on the buggy side, but it also offers a lot of depth and interesting historical facts.
Patrician 3 is another economics game, which offers a lot of interesting choices. I would recommend going straight for te 3rd game and skip the first two, after all, there is no connecting story.
The guild deals with things on a slightly smaller scale, but offers a deep & interesting experience as well. You basically run a guild during the 15th century (though the game also lets you do some more illegal things). I thought that The guild 2 was better, but most people seem to find the first game to be the one to get.
Capitalism 2. While I've only played the first game in the series, most people seem to think that the second one is better (apart from GOGians it would seem, 2 has a marginally lower average score). The game allows you to buy, trade, sell and manufacture goods, with the end goal of getting as much money as humanly possible.
And to move away from economics games:
Mig Alley is an interesting flight sim that takes place during the Korean war. I for one find most flight sims that takes place later on to be far less interesting, jets fly too fast and dogfights often just comes down to 1hit-1kill in those, but Mig Alley do still offer interesting dogfights.
*edit*
How about
Orbiter? It is a space shuttle simulator, and it is free!