I think travelling before Uni teaches you more than you could ever learn working. Not necessarily academic things, but it'll teach you a lot about the world and independence which will be pretty useful. This is all just speculation of though since I've not left for my gap year yet! I say do it.
Gap years are good if they are productive. Travelling and 'working' don't have to be separate. You could always do a little volunteer work as you travel which would look good on your CV and be interesting. Either way travelling is a general great life experience. Enjoy your freedom while you have it and develop your levels of independence.
I went travelling quite a bit when I was younger (by myself) so I didn't want to travel in my gap year - i've already done the 'finding myself' thing. I didn't plan to have a gap year but now i have, it was a good decision.
i've made much more informed decisions about unis and i've got some great experience which will help me get a job when I've finished uni! I'm also really looking forward to working hard at uni, whereas last year I was fed up with school and would have just messed about in my first year.
Maybe I'm not normal, but I'd be crapping myself if I was going to go travelling around the world alone. Do people generally go alone? I'd just have no clue what I was doing, and I'd be so nervous. I can imagine it'd be a really great experience though - good in developing loads of life skills! Where do people get the money for it though?!