I too wasted weeks of my
childhood with my dad's old
tape recorder or later his
ghetto blaster shouting the most creative thoughts my mind could muster into the little slits of the
mic - I even had a TV station (without pictures) called
DWEEB TV which spanned a dozen cheap
dollar store tapes.
Steering away from GTKY territory, there are still ways to experience those heady days of babbling into a microphone and cringing at your voice as everyone else knows it.
The first of these is that faithful minidisc. Never really catching on, it has a following of obsessive fans (like me) who maintain it is a viable, more frugal substitute for expensive MP3 players. You can do virtually everything with a little minidisc walkman that you can with a tape recorder. Plug it into something with phono cables and record music from a hi-fi or radio; or plug in a microphone and record live. Granted, kids today probably won't hanker after them in the same way we children of the 70s and 80s did for tapes, but the potential is there if you want to relive your childhood.
The other lovely means is the camera phone. All you need is a modern cellular phone (waves Nokia 6230 tauntingly) and you can hit a button to record virtually unlimited amounts of audio by simply pointing the phone at what you're trying to record. Where these phones take fun into realms we couldn't have dreamt of as kids is with their photo and video capabilities. Never mind the still pictures, recording full-motion colour video with sound on a whim is truly the evolution of sitting in your spare room recording the world and playing it back in fascination.
Go out and document whatever takes your fancy - just like when you were a kid. Be creative. Don't worry if it bores you now, in the future you'll treasure every last snippet you save now.