Originally Posted by flicker
GPS with chart plotter,
manual bilge pump,
diesel or propane stove/oven,
refrigerator or freezer or ice box,
Much of this really depends on what kind of sailing you intend to be doing.
Self-steering vanes are great for long bluewater passages, but not so useful for other places, where the winds may be more variable, or the courses require tacking more often.
Radar is also another item that may not be necessary. It also requires quite a bit of power to operate and a fair amount of practice to interpret properly.
GPS Chart plotters are pretty nice, regardless of what you're doing, but if you're going to go off shore, a sextant and nautical almanac are a good idea as well, as electronics are vulnerable to multiple types of failure. Paper charts and good navigation practices are also highly recommended.
Water Purifiers aren't all that useful, but Reverse Osmosis Watermakers are very useful. Most require a fairly expensive installation, and a fair amount of electricity to run. I prefer to get a simpler, non-electric model, like the Waterlog 100.
Manual Bilge Pumps are always a good idea. So are having a few sturdy buckets...as there is little as good as a scared sailor with a bucket for bailing.
Modern headsail roller furling gear is quite good now... and i highly recommend it to make sailing both safer and more convenient. The mainsail furling gear isn't quite ready for prime time IMHO.
Generators are over-rated, noisy, and can be a pain to maintain. Alternate forms of power generation are probably a good idea. I am using solar panels, as they're quiet and reliable. Wind generators and water generators are also good options, and less maintenance and noise than a generator.
Stove/Refrigerator/Cooler are nice conveniences. Much depends on how you are going to use the boat.
Survival Suits-A really good idea if you're sailing in cold water areas or cooler weather. IMHO, they are a necessity, as hypothermia is a killer.
If you want any more advice, drop me a note.