For the last couple of weeks I've been thinking about writing a weather application. Not serious yet, just mulling it over during downtime as you do. I used to write this sort of thing for a living (in C but) so I have a good handle on it.
When I'm in this 'phase' it usually takes one small discovery to tip me over the edge and start me coding. Something that makes me say "hey that's pretty cool, I might have a play with that". And then we're off on a mad coding binge 
Right at the most opportune time Hans Fugal releases ruby-wx. Perfect!
"So what?", you say. Well this is the third or fourth time this has happened to me in the last year and it's starting to freak me out. Right when I have some gnarly problem ruby pops up with exactly the thing I need. Hpricot being the spookiest before now.
I know Ruby practices the principal of least surprise but this is ridiculous.