The last variant on boom-boom I gave had fairly slow, plodding play. I've since come up with the following game, which is by far the best board game I've ever invented:
Play is done on an othello board, with both players having one color and moving alternately. On a turn, a player may either place a new piece in an empty square, or 'explode' a piece they already have. Placed pieces may not touch an opponent's piece on either a side or corner.
To explode a piece, the player places one of their pieces in each of the eight spaces touching the piece they exploded. If a piece is already there, it's left alone. A piece may not be exploded if it's already completely surrounded. After a piece is exploded, all opponent pieces which border on the exploded piece (either edges or corners) are flipped over, then all opponent piece which border on those are flipped over, and so on, until there aren't any places where two pieces of opposing sides border each other.
The first player to be unable to move on their turn loses.
I've play-tested this game and it went over very well. There are plenty of simple tactics for someone just starting out, and lots deeper and more interesting tactics as you master those. Kids love flipping over so many pieces, and find the rules easy to follow. An 8x8 board is a little small for this game, perhaps it would be good to use that as a beginner board and a larger board for tournament play.
Anyone who wants to follow up to this post should do so via livejournal comments rather than posting to advogato, because I find advogato blog conversations clunky and probably won't follow up to responses there.