I don't generally play burn spells in EDH, but if you want to play them and are using the "X" ones, I highly recommend Mana Echoes. It's a cheap card that can give you a lot of mileage, especially after a Krenko, Mob Boss activation. Maybe replace Lightning Strike? Another consideration is Skirk Prospector.

Also, I would remove Lightning Volley and replace it with Slate of Ancestry since you will need the card draw and will probably have extra colorless off that Mana Echoes.

Lastly, I recommend removing Lightning Bolt and, if you still want the three damage punch, use Lightning Crafter instead. The latter can also protect any Goblin from a board wipe with his "Champion a Goblin" effect.

Goblin Warchief is another great guy to add if you have an extra.

Thanks, griffinpride23, first of all, thanks for the good suggestions... who knows if I ever would have stumbled upon Mana Echoes myself.

Skirk Prospector I should have noticed myself =) but good looking out.

Lightning Crafter could be useful, and Goblin Warchief is missing because I haven't gotten around to buying another one for this deck (which I don't use as much as I'd like--I got two Warchiefs, but they are both in a casual deck currently).

The only thing is I kind of like Lightning Volley, so do you have any other suggestions on what to remove, or do you really think that would be best?

Maybe one of the Creature Auras? You could potentially get two for one'd by using them. Also, Goblinslide seems very limited in this build, as you only have roughly 25 non-creature spells.

If you really like the Lightning Volley effect, then you might also like Furystoke Giant. Just keep in mind that you creatures with summoning sickness still can't tap for the damage.