Forum Moderators: goodroi
Usability - The text from the title tag is shown to users in several places. It is often but not always used in the search engine results page. A more user friendly tag line with some sales pitch included may help to increase the click through rate. Also your title tag is used when people bookmark your page.
Search Engine Ranking - The title tag is a semi-important part of the search engine ranking algorithm. Including your keyword in the title tag generally delivers a boost to your ranking power. Excessive keyword stuffing & duplication may also deliver a lower ranking.
I generally try to keep my title tags shorter, include the main keyword, possibly including the site name at the end of it to help my branding efforts. This helps to balance the need for usability & search engine ranking.