Very interesting ppt on slideshare by David Armano, VP Experience Design, Critical Mass – Micro-interactions in a 2.0 World. The following quote by him sums it up:

“We live in a world where the little things really do matter. Each encounter no matter how brief is a micro interaction which makes a deposit or withdrawal from our rational and emotional subconscious. The sum of these interactions and encounters adds up to how we feel about a particular product, brand or service. Little things. Feelings. They influence our everyday behaviors more than we realize.”