As a software developer I find agile/lean practices in general to be a really awesome way to go about making awesome software. This means that you always shoot for the simplest thing that might possibly work and rapidly produce working software that you can show to your client, get feedback on, and improve. Lots of features that seem like great ideas in the beginning end up getting de-prioritized or thrown out all together and other great ideas are added. In the end the client ends up getting software that meets their needs at minimal cost---plus it's a fun way to work. Just saying "let's go lean" doesn't cut it though; the process of building custom software is complex and keeping the clients ideas and feedback organized and up to date so that work can get done effectively and without confusion is a challenge---especially when working on teams. That is where different agile tools come in. One of which is Scrum.
A little while back I completed my Scrum Master training in NYC. I really love it. Scrum is about making everything visible. At my office we have a Scrum board, onto which we pin user stories in different columns, reflecting whether they are to-do, in-progress or done. There is also space for impediments and tasks that the team needs to take on outside of the usual work of producing code. Each day my team gets together to check-in about which stories we worked on and which we intend to work on before the next check-in. As stories are completed throughout the day we walk up to the board and move the index card with the story written on it to the "done" pile. If at any time you don't know what to do, you can always walk up to the Scrum board and pick a task from the to-do pile and start working on it. At the end of each week the team gets together to reflect upon the previous week and every two weeks (our iteration length) we make a plan for the following iteration. Planning entails committing to complete a number of user stories before the next planning session.
Scrum also calls for a "Scrum Master" who runs interference for the team so that (ideally) nothing distracts them from completing the work for the iteration. The SM may also interface with the client to create and prioritize user stories for the upcoming iterations.