I've got a philips with this feature which I find pretty useful. You have to label your tapes 1 to 9 (thats all it can cope with), and when you insert a tape it asks you to tell it which one it is.
When you record, it saves the channel, date , time and length for each program against that particular tape number (you can afterwards overwrite this with your own text).
When you want to play something you can display all the recordings by tape number on screen, scroll to the one you want and press OK. If the right tape is currently in the VCR it will FF/RW to it and play it for you. If not it pops out the current tape and then prompts you to insert 'Tape X' and then locates/plays it for you.
The more I think about it - the more I wouldn't be without it !
Hope this helps.