I just bought my 7 year old daughter a
Wenger Junior 09.
It is a standard SAK size (85mm blade) but the main blade also locks. Their Junior line is interesting in that the main blade has a rounded tip instead of the traditional SAK drop point. In my case this made the knife a bit more Mom-friendly
.
This model also has the one tool I think is the most useful after the blade: the saw. I think this is especially true for kids who I find will try "sawing" with their main blade at some point anyway.