A couple things I've been meaning to post lately:
One bomb split with

that kills two enemies, one with each copy, will not give you successive crystals. One blue for each.
In NM mode, if you get

you will walk just as slow as it makes you in normal mode. However, when you exit the level, you will walk as if without a

effect! This lasts until death.
^I'll use this as a signature while I concoct one with

....