The developers 9 Square Workshop have taken the route of making diary entries easy as well with their semi-eponymously named 9 Square Diary DX (a free version sans DX is available too). You are presented, upon opening the app with nine tiles making up the vast majority of the screen while five control buttons run across the app's bottom.
Momento from d3i Ltd puts your daily documentation back into the mix by adding in your social media whether it be Twitter, Facebook, Flickr, Instagram, Foursquare, Gowalla, Digg, YouTube, or even the RSS feed to your favorite site (your blog, for instance). $2.99 iphone
Fire up Daily Burn's Meal Snap and you have three basic controls. A vertical calendar of dates on the left, a settings "i" in a flame in the upper right, and a large camera button that looks like a plate with fork and knife. And that's its magic -- its simplicity.