Nice deal on the tank! When I was looking to stock my 40 gallon I saw some peacock eels and thought I might like them until I did some research and found out they dig and didn't fit with my stocking plans since I like one small school of fish in my tanks.
Here is a couple of sites I check out a lot when I want stocking ideas
This one I don't like the suggestions since an eel can grow up to 10 inches
http://www.elmersaquarium.com/10eel_peacock.htm
This one makes sense and says swordtails will be on the menu one day
http://aqualandpetsplus.com/Oddball,%20Spiny%20Eel.htm
Here is one that suggests medium size chiclids
http://badmanstropicalfish.com/profiles/profile96.html
If I was to get a deal like you did and had one eel already I would probably get some type of chiclid or if I was going with an Asian theme I would get a larger Gouramis.