I have experienced this somewhat. I too like to explore new things but I usually find I need a reason to do so. Like, 'Learning LISP would be interesting, but what good would it do me?'
I am always reading posts from guys who just toy around with some random language in some random environment and I wonder why they commit so much time to something that is pretty useless.
Its easy to get into that hole where you do not want to do anything because you cannot easily see the merits behind it. My strategy for overcoming these trenches is usually to move on. Change your environment, find a program at work that could use some creative updates.. etc.
I always find working on projects that benefit me as the best motivation to learn new things. If I see something that could be improved by a redesign or a new pattern I just read a bit about on wikipedia I jump on it. I learn all there is to know about it, write up the project, make sure its perfect, then move on.
This works best in an environment where you are not 100% confident in your knowledge, that way you can see something that you think could be improved, but after research and a bit of consultation you find out you were wrong. And trust me, there is no better lesson then realizing that your initial hypothesis was wrong.
What puts you in that void is the feeling of superiority, the thought 'Yea, I would do it this way, but its not worth my time.' Will kill any and all motivation. If you consistently find your initial thoughts wrong you never end up in that void because you are always underestimating your abilities.
These days I find motivation for new research and developing and learning new things out of the competition with my fellow programmers. I am constantly telling myself I do not know enough, and thanks to wikipedia, stumbleupon, and my RSS feed I am constantly reminded that there are better programmers out there and I still have a long way to go.
So with that in mind I try to put myself into situations where I do not know everything. Situations where I can pick up a broken system, apply some changes, maybe redesign the entire thing, and put it back down to move onto the next. It keeps things interesting, it keeps me motivated, and it makes me a better programmer.