We recommend that you include 1-2 of your most important keyword phrases in the title tag, BUT be careful not to just list keywords. If you just list keywords you risk being viewed as a spamming the engines which can ultimately lead to you being blacklisted by the search engines. Your title tag should include your keyword phrases while remaining as close to a readable sentence as possible to avoid any problems.
Make your title enticing! Don't forget that even if you get that #1 listing in the search engines your listing still needs to say something that makes the surfer want to clickthrough and visit your site.
Since the length of your title tag could be a little long for some engines we suggest placing the keywords at the beginning of the tag when possible so that you do not risk having them cut off.
Each page of your site should have it's own title tag with it's own keywords that related to the page that it appears on.