cool transition effects?

OK, so I'm working on a remake of an old rpg of mine with allegro, so I'm trying to pack it with all the neat little graphics stuff I know. I'm working on the transition from the world map to a fight. What I'm using right now is that the screen flashes, then shrinks down until you can't see it, then comes back as the fight screen with a little message "You're being attacked by a %s!". What I want to do is have a whole stable of transition effects that I can use randomly at the beginning of fights, like maybe a swirling effect or a shattering effect or something wicked cool like that, but I'm not exactly sure how those effects work. Does anybody know where I can get some source/ideas or something on doing this kind of thing? thx

If I'm correct, you're doing this in DOS.
Try a dissolve effect or something, like randomly erase characters on the screen until it's all gone.