I want to know how to utilize my space as much as possible. I have a 1.5TB external hard drive that I have all my games, emulators, and assets. The problems I have are with my CD based systems. The ISOs take up so much space! My systems that are CD based are:
3DO, NEC PC engine CD & Turbo Duo, Sega CD, Dreamcast, Saturn, PS1, PS2.
All of my other systems have all their ROMs zipped. The only reason why I haven't zipped my ISOs and used the gameex zip support setting is because of how long it would take to extract the ISOs. I don't find looking at a black screen for a minute or more particularly appealing, so unless theres something I don't know I'm screwed because i only have 10GB of space left... 
How do you guys maximize the space you have?