There are many reasons to donate.  Sweeten the deal by earning a little cash for doing it. This website offers a list of places that accept plasma.

September 20th, 2009 donate, level 3

Hey, you were going to throw it away anyway! Bring your used containers and gently used clothing items and receive discounts at the following stores.

• Jillplatner.com – Bring in your old gold and receive a credit (market rate minus 5% handling fee) for new jewelry.
• Kiehl’s – Trade empty Kiehl’s products for new products. (3 empties = a lip balm, 5 = travel collection, 10 = full-size product up to $25 value)
• Wink NYC – Bring in a gently used dress and receive a $50 gift card toward something from the new Wink Collection
• Soles4Souls – Drop off any pair of gently worn shoes at 68 Timberland retail locations in exchange for a 10% discount off of a new pair

September 13th, 2009 donate, level 1