Here are some caresheets.
http://ball-pythons.net/forums/showt...is-macularius)
http://allaboutfrogs.org/info/species/grntree.html
Your friend needs to be sure they can provide the correct habitat and food and that their lifestyle will match the needs of any animal they are thinking about keeping. They should also know that many male frogs with croak in some form or fashion and some room mates or paternal units will not find it enjoyable.
Its hard for us to judge the best pet for your friend without knowing him but we can provide info when needed.
If we also knew what they were expecting from the pet it would help.