Thanks for the responses everyone. I need to think about it. I like the saltwater tanks more so fresh would have to be much easier to make it worth it for me.

Sherri/mathias- I'm thinking bare minimum for a 55, substrate- sand or crushed coral-, live rock, flourescent lights and some kind of skimmer (if you keep a real light load in there you could get away with a not so good cheap skimmer I think). More circulation would be nice, but if you do a sump your return will circulate, and if no sump you could just use HOB skimmer which will always provide circulation. Again, I'm just thinking of bare minimum.

Many people would probably say you could do it without live rock, but I think it's so much easier to keep everything balanced with live rock and actually makes for less maintenance.

Someone- Thanks for the offer. I will probably be PMing you if I decide to go freshwater. A bunch of schooling Tiger Barbs in a 55 sounds kind of cool to me, or cichlids...

Vinh- Thanks for the info, I'll remember that if I decide to go freshwater.