In my personal opinion.
IMPO, this is a cool site.
1) In my personal opinion - the personal part really isn't necessary, but this is what it most likely means.
2) In my professional opinion - very ironic, considering someone giving a professional opinion would most likely not use any lazy abbreviations.
1) IMPO, that band is the best!
2) IMPO, I think we are looking at a hippie jam fest of a size we've never seen...