It seems like a bit of a contradiction, but sometimes it works for us.
Most of the time, Billy just seems to naturally flow from one aspect of learning to another. Sometimes though he seems to get 'stuck' and even though he's bored, he needs some help to move on. I've been seeing that lately - he'll complain about the computer game he's playing being "boring" but keep going back to it. I get the same - especially with the computer. I know when I start aimlessly surfing the net looking for new blogs to read, new yahoogroups to join, or when I check my mail or Facebook constantly, that its time for a kickstart. I'm not always able to do that though - I recognise the problem, but often it takes some external event (like being super busy) to drag me away and get me back to doing other things.
So I see my role as providing that external event for Billy. It's my job as facilitator to engage him in something new. I offer the opportunity, and he can decide how far he wants to take it.
On our hike last week, Billy had found and collected some bits of coal (which are now lying all over the loungeroom!), plus we noticed the layers in the rock cuttings we walked through. So I've gathered together some resources on rocks - I used Lesson Pathways for a starting point for some activities. Yesterday we read together "The Magic School Bus: Inside the Earth" - even though I have a list of other rock-related activities, I was quite prepared to leave it at that if he wanted. Instead he asked me eagerly "What else are we doing for Rock Week?" He's decided he likes having special weeks where we learn about a topic, and has looked through the book we have of History hands-on activities, and declared the next week to be Viking Week!
Disclaimer: If you think I'm breaking some "rule" of natural learning, then that's fine - I'll just fall back on my "eclectic" label :) We do what works for us.