Nothing beats google!
I think what you need is something called Pyrocluster...
Here's a direct link:
Since I haven't got Truespace, I can't verify exactly what the download is, but according to the webpage, that's some sort of update pack that installs the Pyrocluster explosion plugin.
Fingers crossed it does install it, coz I saw some websites selling the plugin for as much as $700... 8O
There were other plugins available, (Not necessarily explosion-based) so if you want to checkout the page it was on, here you go:
Hope that helps.
