prMac (
http://prmac.com/) is a must have for any iOS developer. They do a great job of publishing your press releases and getting them picked up by blogs or newspapers. Their customer service is also the best I've experienced. You can even get them to write a professional press release for you and send it to an extended number of publications, all for a low price.
Technology, hacker, or iPhone blogs are also a great place to notify about your app. Use Got O.A.T.S.? (http://www.gotoats.org/) to find the blogs that have the best ethics and will never do paid-for-reviews. Make sure to send each of the blogs listed on that page a friendly email with photos, video, promo codes, and a description of your app. Only a small percentage will review it, so don't be afraid to write to dozens of blogs.
Facebook, Twitter, Reddit, and other social sites are also good marketing tools. Make good use of them.
Hope this information helps! Good luck!