Well I used to copy cracked C64 games and later Atari ST games, although that's more the 'cracking' scene than 'modding' scene. I knew of stuff like SuperUFO and MagicDrives for the 16bit consoles because some rich kids at school had them, but I didn't have either of those consoles so I wasn't really involved in that scene. Indeed my next games console after my ST (Well, apart from a GameGear) was a PSX. Once modchips appeared a guy at a local market started modding them and selling 'golds' as we called them then for a tenner a time. Seems like a rip off now, but bear in mind hardly anyone had a CD burner back then, Blank CDs cost a fortune, PSX games were about £35-£40 and even more if you imported them from the US months before the PAL release.
In terms of flashcarts, I've still got a Dr64 GBC cart somewhere, which was awesome. I'd started playing a GB game called "Pocket Monsters" on an emulator. I'd never heard of it and neither had anyone else over here but someone on a newsgroup said it was cool so I gave it a shot - after all, it was only 300k which was a lot eaiser on my poor modem than the Class and Myth rips I'd been racking up a huge internet bill on. I also gave a copy of it to a girl I was friends with at school and we'd talk about evolving our Wartortle in the pub, much to the confusion of everyone else. When the Pokemon cartoon came out I was amazed they'd actually made a cartoon of the game - little did I know the huge mutli-product marketing machine that would take over the country later.
Anyhow, I got a student loan through and decided I was sick of playing GB and GBC games emulated, so I got my GBC and flashcart from Lik-Sang. From sitting around on IRC Channels I got access to a scene site through a friend. and I was getting games as soon as they pred which was also awesome, especially seeing the new cracktros and trainers which reminded me a lot of the C64 scene. Started posting games on newsgroups through my 56k modem and even helped get some NGPC games dumped. Strangely enough, I skipped the GBA. By this time I'd lost access from the site during a regular clearout of users who siteops didn't recognise and my contact wasn't authorised to re-add me because of increased security around sites at that time. I didn't have the money to buy a flash cart, GBA games were bigger and I was still paying for the internet by the minute. When the DS came out I had a good job and lots of disposable income so bought it on day one and kept myself up to date with attempts to make GBA carts run nds code (my leeching hunger had been fed in the meantime by the excellent DreamCast). Finally I bought a SC and a pass-me, flashed my DS and started playing all the aweseom games I'd been missing out on (I had a pretty big collection of originals, but Euro releases were sometimes years behind their US counterparts) Eventually I got sick of patching everything and waiting for updates, so when the R4 came out and got such a great GBA Temp review I ordered one straight away, then upgraded to a DS Lite the same week. Since then I've ordered another 8 for friends. The End.