I find the odd hour here, hour there to be a real problem for me. It takes me at least 5-10 minutes to get into a working mode. When I have only an hour or so, it makes me reluctant to try to get work done in those small spans of time, which of course creates a time sink or at least some undesired entropy.

So, like ebrodeur said, I would see where I could streamline my schedule. This includes getting as many things done at once so you have larger blocks of time to do stuff that matters. I know this is easier said than done. I am a student and I frequently have an hour here and there between classes that is extremely frustrating to try to get things done.

The other thing I wonder about is how long you have left on your degree. Since you're in gen ed classes atm, then it sounds like you have a ways to go. In this case, the obvious thing to do is bust ass while you are on breaks such as Thanksgiving, winter/Christmas, spring break, and summer. I would identify ahead of time what exactly I wanted to work on during those times and "snowball" my time that was vacated by classes into working on that. I know you'll need to rest and recuperate for the coming term, but these are precious chunks of time.

There is another way to steal away some time if you are a pretty good student. For me, I don't have to pay a whole lot of attention during classes (I'm writing this post in class right now, for instance.) in order to maintain good grades. (I currently rock a 4.0. Not to brag, just to say it's not sacrificing my grades.) If you're in gen ed classes, let's be honest, those don't really matter all that much in your grand scheme. I'm all for well-roundedness, but we're dealing with extreme situations here. If you are a little older, chances are you know a lot of the stuff you're covering in those classes anyway and won't take a lot of value away from them. So, if you have a laptop, work on RoR in class. If laptops aren't allowed, (I had a psychotic prof who wouldn't allow laptops in class.) brainstorm and plan on paper. Brainstorm your models. Identify what controllers and/or methods you will need. Draw your views and identify what needs to be done to make the views reality. I wouldn't write a line of code on paper just because you do not want to duplicate any efforts.

Finally, I think that if you have a specific idea and aren't interested in doing RoR in general that you might consider hooking up with some other developer(s) to get the project going. Chances are there (I know it's true for me.) are aspects of the development that you are better at than others. If you can team up with other developer(s) for those weaker areas your project can take off faster and likely be higher quality.

OK, sorry for another long-winded post, but I hope I have some helpful things to say.