yep, you said it - can of worms. The most simple and most effective way that I have found of getting a listing on google is to link from another site that is already been spidered by google i.e. maybe even this forum, by putting your site link in your signature
The easiest way of getting a "good" listing on google is to have a link from a site that is both relevant to your site and has a good page rank. You can tell what page rank (x/10) a site has if you download the google toolbar and put your mouse over the page rank bit.
I am no expert but these are the methods I have used with a fair amount of success to get both my sites spidered and some good listings for targeted keywords in Google. The others - Msn, Yahoo etc, I do not have a clue but I generally think if Google likes you then you'll get a lot of traffic anyway and whatever else comes is a bonus.