This is strictly from my experience and knowledge as a native Japanese speaker... 'jibun' means oneself (or myself, yourself, herself... depending on the context), but in some context, it has the same meaning as 'watashi'. I feel that jibun as watashi is used mostly by very masculine men... not so much by women. 'Jibun' is sometimes used as 'you' in the Kansai area in Japan. I would stick with using 'watashi' or 'boku' (if you're a male). oneself: これは全部自分でやりました。I did this all by myself. 宿題は自分でやりましょう。Do your homework by yourself. me, my: これは自分（私）の責任です。This is my fault. 自分（私）がやります。I will do it.

I think HCast is right. Sorry Michael, I've just given you a variety of usages of personal pronouns. I was misreading and also I've been writing another one. But I quitted just now. for male: 「わたし」is used in public such as business. Students use「ぼく」in public. 「おれ」is informal, but many men use this. Then「じぶん」,「せっしゃ」and「わがはい」← use this whenever you think yourself a cat♪

for female: 「わたし」is the most common as you know. 「わたくし」is the most polite one. You shouldn't use these following in public.「あたし」is used when with your family and friends. You can hear this from many TV personalities.「あたい」is now old fashioned, bad girls used to say. Just remember this for fun. Now many kids call「うち」to themselves. Sorry, I can't tell you exactly but in some certain places of Tokyo, Osaka and so on.