A number of new fantasy sports sites have popped in the past two years that have daily and weekly contests, rather than season long competitions. In some ways, these sites have a lot in common with poker sites, and the contests definitely appeal to those who like sports gambling. These sites include Fantasysportslive, Snapdraft, and the new kid on the block - Draft Hero (see information towards upper right corner of browser).
Strategy for these games places a heavy emphasis on your ability to adjust for context, and adjust player projections for factors such as park, homefield advantage, platoon differentials, and opponent. But the most single most important factor in your success is going to be something much more basic...and much more boring. Select your players as late as possible, so that you can make sure that they're in the starting lineup! This isn't a situation where you've got a full season to reach some sort of games or innings pitched limit. If a player isn't in the lineup, that's going to be compromise your chances in a big way, and with most players getting the occaisonal day off this can make a big difference over the course of the season.