A tutorial I had alot of fun with, in which was placed in the Top 10 Tutorials of 2011 on Blender Guru, and am still inspired to play with, uses Smoke particles to create an impressive looking Flamethrower..
Smoke & the particle system in general is alot of fun to play with, so here's a thumbnail & an additional link at the bottom if you're able to view it that may inspire you to delve into the wealth of resources available.
If you're interested here's some eyegasms/examples of blender smoke effects that'll leave you in awe :)