Does Google ban for this? A lot of people are doing it. Has there been any talk of people getting banned for it?
"Buying Adwords and sending them to landingpages"?? That's exactly what AdWords is for. You should take a look at the Google AdWords Landing Page and Site Quality Guidelines.
No I mean a landing page from another company, like Azoogle or some other company. Like the ringtone guys do. What I'm basically asking, does there have to be decent content (or content at all) on my site that I'm going to advertise, or just can I put an ad for a product?
unless the page your directing your customers to is completly irrelevant to the ad shown then theres no ads that are denied. well except the obvious illegal sites, but then again theyre pretty lenient on them too, for example torrent sites. So basically theres no real restrictions. If your talking about an affliate program, then yes of course you can. Is this "landing page" top secret?
It fair game but makes for a crappy experience for the web user. If done right, you can make some good coin though.