A website is pretty much standard stuff for any business these days, part of the marketing package along with business cards and letterhead. Designing a Website for a Coffee House, by Michael Allen Smith, gives coffee shop owners some good advice for an effective web presence. The list includes The Basics (where you are, what you do, what you sell), and some great ideas for drawing repeat traffic such as a webcam, and offering internet specials and coupons.
A webcam is such a great idea. It changes day to day without you having to do a thing, solving the problem of keeping content fresh and up-to-date on a tight time budget. Of course, running a webcam has its own demands and headaches, including servers, bandwidth, cameras, etc. To learn more about setting up a webcam, check out the Webcam Setup Guide.
One step down from the live web cam, but still a good idea for fresh content with small time investment - a blog where you can post happenings and pictures. A blog is easier for a novice to update than a website, and lends itself to search engine traffic in a way that static websites don't. Besides, it feels more personal than a website. (I really enjoyed watching the progress of Pioneer Coffee Roastery as they prepared for opening and beyond.) Photos don't require a lot of typing, time or thought, and still give repeat visitors a view of your atmosphere, the creations of your barista, your customers, any new delish baked creations, etc.
A static website is still essential, but supplement it with a blog and you've got it all.