Randfish at SEOmoz has posted an interesting article on how to come up with best possible title tags.
Randfish advises to use the title of the site or brand either in the beginning or during the end of the tag to help the searchers locate where they are heading. The length should not exceed 65 to 70 characters, which should be inclusive of spaces.
He further apprizes, “Incorporate keyword phrases. This one may seem obvious, but it's critical that whatever your keyword research shows as being the most valuable for capturing searches gets prominently included in your title tag. Moreover, it is advisable to use dividers to separate the site name or brand from the description. He adds, “The title tag is exceptionally similar to the title you might write for paid search ads, only it's harder to measure and improve because the stats aren't provided for you as easily.”
Catch the full writeup.