This came up recently and I wanted to give some detail and get feedback:
The three significant new ranger traditions are: modern, mundane, and psionic. They are defined below. If a ranger chooses one of these other traditions, he may also choose one of the earlier traditions and combine skill sets. A common example is the Urban Modern Ranger. In any of these cases, the ranger does not get double the number of abilities. If there is a conflict, he must choose which one he prefers. In the Urban Modern ranger as an example, at first level, he may choose between Technology and City Familiarity.