Making juice from fresh fruit
The easiest way would be to use an actual juicing machine. Instead of just blending everything together, a juicer will separate the juice from the pulp.

You're looking for something like this:

http://www.amazon.com/Hamilton-Beach-67650-Mouth-Extractor/dp/B000FHQJ6C/ref=sr_1_7?ie=UTF8&amp;qid=1292255706&amp;sr=8-7

Juice goes out one end, pulp out the other.