I think that most collectors eventually get to a point (usually once junk starts to accumulate) where you ask yourself - do I really need all those games? the obvious answer is no but what if you get rid of it all then you might regret it when you want to play a certain game in the future?
the answer is having ways to load the ROMs for each system without the original software. this is nothing new ofcourse but there are different ways of doing this for each system. so if you do this share how you do it. This is how I do it:
Super NES - download ROM from internet, split/fix with SNESTool, copy to floppy disk, load floppy disk with copier device (UFO Super Drive Pro 6 in my case). if you have a better copier (e.g disk doctor SF7) you can load ROMs directly from PC using SNESTool via male/male parallel cable
Sega SC-3000 - obtain a WAV file of the tape ROM, plug a standard stereo cable with mono plug from PC output (eg headphone socket) to SC-3000 input (cassette IN), type LOAD on the Sega and play the sound file through your PC. note - Tape drive is not needed to do this!!
tape ROMs can be found on sc-3000.com and can be loaded directly from that site. however plug your PC sound out into your sound in with a stereo cable and you can record it so you have your own backup on your HDD. vortex blaster in WAV format can be found here - http://www.stickfreaks.com/sc3000h.php
Commodore 64 - obtain tape dump from internet, convert to WAV file using utility (have to check which one when I get home), connect PC sound output to a tape drive/player input (e.g Sega SR-1000), press record on drive and play sound file on the PC, repeat a few times so you have multiple games on one tape, load the same as any other C64 tape
CD Interactive - obtain image of a ROM (e.g BIN + CUE file) either by internet or backup, burn to a decent CD-R on slow speed with a certain program (alcohol 120% worked for me), load just like any other CD-i disc.