We were in WDW in September of last year. We were hanging out on the Boardwalk waiting to watch Illuminations cause we didn't feel like dealing with the park crowd. We had just finished eating at Yachtsman. One of the captains (I'll withhold his name just in case they can get in trouble for this), a very nice fellow, told us that the people who had reserved his boat were no-shows and that we could have the cruise for free.
Not only are those cruises fairly expensive, but they are VERY difficult to actually GET because they are booked so far in advance. Needless to say the fireworks were AWESOME (Illuminations is my favorite) and the experience was just fabulous all around. One of the cool things that could only really happen in WDW.