I found a great resource online called ehow.com and it told me things like:
*Water, dried peppers, onions, garlic & a drop of dish soap
*planting garlic bulbs to repel japanese beetles & aphids
* sprinkle diatomaceous earth and or table salt & flour for snails and slugs
*cooking oil & soapy water on fruit trees to smother eggs
*1 lb of cedar chips soaked in 1 gal water, let stand for 2 hrs then use liquid for beetles
*plant pennyroyal or Eucalyptus to repel mosquitoes & gnats
*sprinkle dry borax for ants
*slug/snail trap almost empty beer can on side
* yellow pan w/woapy water-aphids & beetles
*mix rhubarb leaves & water -or- tobacco leaves & water to make toxic pesticide (harmful to humans too so use w/care. /don’t spray on tomatoes but safe for gardens and flowers
and last but not least
*capture a handful of the problem insects – blend them into a paste – ground up insects will repel their own kind ! iieew!!! D… ha…lol

good luck
References :
ehow.com