Install a floppy drive!

Install a serial port!

Do the VGA hack to use an external display!

Those are real hacks, though, and require some reworking with solder (well, the VGA hack might not, but whatever). The ones you mention aren't really hacks (though installing a 333 MHz G3 isn't exactly a supported upgrade) but are definitely good aftermarket upgrades to perform. RAM and VRAM are user-serviceable parts, so that should be pretty easy to do.

Peace,

Drew