Downloaded Bryce 5.5 (apparently, it's been a free download since 2007). Haven't had a chance to play with it much (it finished installing about 20 minutes before I went to bed), but it has some neat features that weren't available in my old copy of Bryce 3.1, like an on-board tree generator, and something called (I shit you not) 'metaballs'. (Basically, it's spheroid objects that blend into one another based on proximity.)

So I should be posting some stuff once I get the hang of the new features.