Then, there is my favourite boat book of all time. Written in a humorous vein and packed with the best little 'fixes' and plans for the improvement of one's vessel. No serious sailor should be without this. Just for the sake of saying it, I have bought three over time. The moral of the tale, don't ever, ever, loan this book! And, the hardcover is a nuisance on a boat...buy the paperback.
Floating phone pouch.
Mini bluetooth speaker.
Hand held depth sounder
And, the new generation of small LED flashlights are unbelievably good
Hope this helps.