Hi everyone, looking for thoughts on my next piece of gear. I'm having a great time with my D60. I find myself looking at lots of gear porn (so to speak). The limitations I've run into so far is the fact that both my lenses are kinda slow. The way I see it, there's two ways to handle this limitation: buy faster glass or buy a speedlight. A flash unit seems to be the most cost effective solution. Now the real queston is which one to get. I'm looking at a SB-600 on craigslist (yes, I will check it out before I buy). The SB-900 is way out of my price range plus has features I'd probably never use. Ths SB-400 seem like it's missing some features that I would use. Any thoughts on these flashes?