I would recommend the little known Google Maps. It's now added a 'walking' route (rather than just for cars) so it ignores one-way streets. Perfect for cycling then too... Hmm...

For example: http://maps.google.co.uk/maps?f=d&saddr=w11+1ph&daddr=nw3+1nn&hl=en&geoc...

It's not perfect, but you can drag the lines around too if you want to make it more direct or you wnat to go by ye organic local farmers market, or whatever.