Re: kickstarter
For the projects, it's a way to get cheap and easy financing (and free marketing, testing platform, etc etc).
But don't think for a second that you become their investor in the conventional sense... what you're doing is just joining in an early group-buy\preorder, and maybe you get some recognition, etc... but no, you're not gonna own any shares in said project/company and your future benefit may just to be in their mailing\discount list.
But with that said, it's a great platform to find new stuff.. I've backed hundreds of projects there and it's much more responsible than other crowd funding platform (i.e.: Indiegogo, ugh).