had a demo yesterday of Visual Passage Planner referred to in talbot's link. it's quite clever - it takes the wind statistics and tells you for each leg of a passage the % of time you expect to be beating, reaching and running, the time taken, distance sailed etc. if you zoom in on a patch of sea the roses appear, including ones for current which are only covered very sketchily on the admiralty pilot charts.
on the other hand it costs £99 which would only be worth paying if you were planning a lot of long passages.
I have a copy of VPP which I've had for the last two years. I bought mine directly from the US, from where it originates, and paid $99 plus P&P. As you say it is not cheap but it takes alot of the slog out out the 'what if' type of queries when you are working out routes in unfamiliar areas. I believe that the wind and current rose data comes from the same US/UK database that is used to produce the Ocean pilots.