Use .save to avoid any significant rollbacks.
To improve your weapon skills write .maxskill
To reset instances so you can re-group with new people and still enter an instance you just completed write the following command: .i u all - And you can re-group.
To talk in our world chat simply write .chat / .w / .wc / .c
Use .buff - Buffed.
Use .learn all lang - Learn all languages
Use .learn all my pettalents - Learn all talents for your pet available for his creature type (only for hunter pets)
Use .learn all my talents - Learn all talents (and spells with first rank learned as talent) available for his class.