TNT in Minecraft can be very useful, and not just for blowing up huge holes in the ground! (see here too)
A single block of TNT takes out an 8×8 cube of blocks. Burrow into a cube, plant that TNT and step back and you clear away stuff at a decent rate! You’ll want to read this wiki page on the subject too!
throw one into lava and make yourself a volcanic eruption 🙂
Yeah, setting TNT near lava is asking for trouble. I did it once and when I saw the explosive smouldering and lighting I ran for it!
And what was the result? Fireballs?