Microsoft have released Master Page samples, which you can use and adapt to your WSS v3 sites, and which you can download from this URL:- http://www.microsoft.com/downloads/details.aspx?familyid=7c05ca44-869a-463b-84d7-57b053711a96&displaylang=en&tm.
There are 4 different styles of master page - block, clarity, horizon, reverse - each with 5 different color variances - blue, green, orange, purple and red. I've included some sample screen shots. below.
