For "free" marketing techniques : -Add your app to your forum signatures wherever you post most often -Twitter giveaways -Tell your friends and family -Submit to review sites/ blogs (In my experience you might try small blogs first unless you have connections at a major blog or think your app is mind blowing)
For paid techniques: -iAds (I haven't seen conversion numbers yet) -Admob/Adwords/etc (No one that I know has had success with this) -Pay per install
Disclaimer: I own and am just launching a pay per install company called adsreloaded.com (there was another thread about this launch in which people seemed skeptical on the idea, but I also received interested from a few developers). If you are interested I have a special offer in which the 25% cut I usually take is added to your campaign instead. If you aren't interested I hope some suggestions of mine do help :)
1) Give the app to industry bloggers, writers and anyone willing to listen to your pitch 2) Submit your app to as many directories as possible 3) Find where your target demo congregates online and become active there 4) Consider an affiliate program to induce sales (banner ads) 5) Rinse and repeat...