Major search engines give a great deal of relevance to keywords in the TITLE tag. As such, you should always include the Title tag along with your most important keywords on every page.
In general, I have found that short keyword rich title descriptions work best, as this maximizes the keyword density.
Here are some examples of good title tags:
<TITLE>WebPosition Gold Review</TITLE>
<TITLE>Canon Digital Camera</TITLE>
<TITLE>Cheap Flights</TITLE>
And examples of poor title tags:
<TITLE>WebPosition Gold – Search Engine Optimization Software</TITLE>
<TITLE>Up To 50% Off Digital Cameras</TITLE>
<TITLE>Cheap flights, tickets, air travel and much more!</TITLE>