I’d like to discuss game content generators to use with GD. Some of which you probably know, others you don’t.
SFXR - Great sound effects generator, especially useful, if you’re going after retro feel.
Charas-Project generators - Main purpose of those is to make generation of RPG Maker 2000/2003 graphics, but nothing stops you from using it in GD game. Warning: RPG Maker character converter won’t work here. It is for XP format of characters. You’ll have to use Spritesheet converter. Select generator at the top of the page.
I’m planning also to write my own GFX generator using Lazarus IDE, but I didn’t decided yet how advanced it’ll be. Though I’ll make it open source.