Do Marigolds Benefit the Garden?

I've been researching the claim that marigolds in the garden will keep away rabbits, Japanese beetles, mosquitos, cucumber beetles and snakes.  Many have differing opinions on whether these cute little annuals can really carry out all those jobs.

The trick seems to be that you must plant the old fashioned variety, you know, the ones with the most smell.  This is what repels most insects and apparently snakes.

Reportedly another use is boiling the petals in water and dispensing this solution into any containers of standing water in your yard.  It is said to kill the mosquito larvae immediately.

Marigolds are very easy to grow from seed, so I think I'll give it a try.  Especially because I have cucumbers, rabbits, Japanese beetles, mosquitoes and snakes!