Rhubarb Tea

Rhubarb's talents extend beyond pies and cakes. In fact, scientists have
discovered that the oxalic acid in rhubarb stems (the same stuff that makes
your lips pucker) can be used to scour cooking pots.
If aphids are pest in your garden, rhubarb can help. In her book, "Slug Bread &
Beheaded Thistles," author Ellen Sandbeck describes a unique use for
rhubarb leaves--as an aphid spray. Here's the recipe:1) Chop 3 to 5 rhubarb leaves
and add to a quart of water. 2) Boil for 30 minutes.3) Strain and add a dash of liquid, non-detergent, soap.4) Fill spray bottle with liquid and use it on aphids.

Note: Because rhubarb leaves are poisonous, don't use this spray on edible plants

From http://www.plantea.com/rhubarb.htm