I've put quite a few miles on my cruiser, but really haven't run in any accessory needs that were unique to them. But some ideas:
-Water bottle mounts for frames without brazeons, and preferably where they can be rotated to mount on handlebars. REI has some, I think, and Walmart has some, but the Walmart ones can't be rotated.
-Racks and rack clips for frames without the mounting points for racks.
-High quality rubber-block type pedals. I can find rubber-block/platform pedals (the name varies), but they're pretty cheaply made. And the more expensive peg-type Wellgo pedals, I've heard good things on durability but don't care for the style.
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"be careful this rando stuff is addictive and dan's the 'pusher'."