A good developer, designer, or creator of anything strives to allow users to experience this kind of flow. The irony of flow in design is that when it is achieved, the design itself often goes unnoticed. Paper clips, suspension bridges, and the computer mouse are all great designs, but are noticed by most only when they fail. This traps the egos of many developers and designers, who might feel frustrated by the lack of recognition for their brilliance. Sometimes you'll see a software product or Web site that goes out of its way to make you aware of what the designer has done for you, or what they think about the world, but this is rarely of benefit to the user.
True design includes personal restraint to avoid tainting user flow with designer or developer ego.
In most cases, if the user noticed something, or had cause to forget their desire and think about the mechanics, you've blown it already. It's a poor tool that places itself before its purpose. To achieve flow, you have to invest from the first day of your project. Every page and every element of your site has to be created with the user's perspective at the core of your thinking. The easiest way to achieve this is through asking questions of your sketches and designs as you create them, before you bring them into the usability lab.