Causative, Passive, Passive-Causative and Natural Potential Verb Forms
Below is a chart summarizing the causative, passive, passive-causative and natural potential verb forms. I stole it from the most excellent book, Making Sense of Japanese by Jay Rubin. I can't recommend this book enough – it is one of the best study books I have purchased and it provides the best discussion of wa and ga I have seen. All chart entries are complete sentences, with implied subjects, objects, and agents, using the transitive verb kaku (書く- to write). All the verb forms have been put into the perfective –た form as you would most likely encounter them in real-life and they have been translated using first-person singular subjects and masculine third-person singular pronouns for simplicity, employing the feminine at two points to indicate the presence of a third party. The emphasis here is on the number of players involved and direction of the action, not levels of respect.

書いた。 Kaita.	I wrote it.
書いてやった。 Kaite yatta/ageta.	I wrote it for him.
書いてくれた/くださった。 Kaite kureta/kudasatta.	He wrote it for me.
書いてもらった/ いただいた。 Kaite moratta/itadaita.	I got him to write it for me.
書かせた。 Kakaseta.	I made/let him write it.
書かせてくれた/くださった。 Kakasete kureta/kudasatta.	He did me the favor of making/letter her/me write it.
書かせてもらった/いただいた。 Kakasete moratta/itadaita.	I got him to let me write it, or I got him to make/let her write it.
書かせてあげた/やった。 Kakasete ageta/yatta.	I let/made him write it.
書かれた。 Kakareta.	It was written, or I was adversely affected by his having written it.
手紙が書かれた。 Tegami ga kakareta.	The letter was written.
手紙を書かれた。 Tegami o kakareta.	I suffered the consequences of his writing the letter.
書かせられた。 Kakaserareta.	I was forced by him to write it.
書いてあった。 Kaite atta.	It had been written. (false passive)
書けた。 Kaketa.	It successfully wrote itself.