...ActiveCaptain only works when you have an active internet connection.
It most surely doesn't need to work that way and every day, more offline use is being built.
It's true that the ActiveCaptain web site requires you to be online to access the marinas, anchorages, bridges, inlets, West Marine locations, hazards, and on and on. But there is absolutely no reason that this data couldn't exist offline on any device. In fact, at the Miami Boat Show (Feb 2010), MaxSea and Furuno showed that exact thing - the entire ActiveCaptain database offline on a PC for access any time. They also have synchronization capabilities so when you get an internet connection, it will sync with the ActiveCaptain servers to get the very latest updates, reviews, etc.
Here's video I shot of the Furuno product manager showing the data offline:
This exact type of capability can and will exist on the iPhone and iPad. It's development that is happening today, right now. You're also going to see the data offline on many other devices and inside many other software products.
I'm really excited about the iPad and I created the design shot that was picked up by Panbo (and an upcoming Yachting Magazine article). It's not that the iPad is so wonderful - it might be but without seeing it I'm holding off final judgement. But what the iPad represents is a large, programmable surface that us developers (and cruisers) can take and use to create new things with. It's a wonderful blank canvas. Apple's version of it might not be the "one" or it could be huge. Let's give it a try.