I just bought a new suit for lap swimming and while it is not very fashionable, I feel like it helps me swim very fast.
One thing that also helps with speed when swimming freestyle, aside from a shiny black racer back suit, is keeping your nose pointed toward the bottom of the pool. This will aim the top of your head toward the direction you are swimming. Another way to think about it is to
Now if you're looking to swim so you can put this tip to work, try this workout: Get It Up - Your Heart Rate, That Is: Swimming.