I am helping with a stealth startup that will use Adwords predominantly for its advertising. What other effective paid advertising tools are out there. Creative responses would be great too.
For paid ads, I like searching the Adbrite.com directory for bargains. Find sites with 500 to 5000 hits a day. Pay the default .05 cents per CPM and you will be paying .05 to .25cents a day to reach all of those people. Finding the right sites is a bit of a challenge but you only have to find a few sites and stick with those to drive new traffic to your site every day.
I have had great luck with StumbleUpon advertising, but it really depends on the site you're trying to promote. The problem with SU is that you need to capture the user in the first few seconds, or they're just going to click "stumble" and bounce to the next site. But if you do have a fun/interesting/cool site, SU is a great source for consistent and cheap traffic ($0.05 per visitor).
I actually used it once to advertise my blog. It worked fairly well, but I wasn't really interested in advertising my blog; I was just interested in trying Project Wonderful.
Stick with AdWords initially and worry about it more later. Until you have a significant amount of traffic no one cares about you. Once you do have traffic you can try out a bunch of ad networks until you find the best one(s) for your site.
There's also interesting affiliate programs. Everyone knows about Amazon's affiliate program. There's also Linkshare.com that represents a large number of web sites as well as numerous web sites that have an affiliate link.
We use Share A Sale for our (newly launched) affiliate program. However, the bigger sites generally aren't in their network, so you don't get top tier placement across the web.
really depends on what your app does and what market it targets. there are tons of specialized ad networks that work to maximize revenue based on what you're doing.
or you could go down the route of obtaining sponsors/advertisers yourself, and managing ads on your own. cut out the middleman, get a bigger profit, but have to deal with the overhead of it yourself.