So your coming to Haiti via the Peace Corps
Jen and I read all the books such as so you wanna join the peace corps, the official peace corps manual etc etc.   We did only pack a what we could carry (She had backpacked Europe and I liked to camp so we had no problems on that end) but some of the items that were suggested or recommended we never ended up using. 

    First of all don't bring a blazer if your a male.  Complete and utter waste of space.  You'll wear it at swearing in only and then almost die from heat in the process of trying to look "professional".  It is the Peace Corps.  If you bring rechargeable batteries bring a plug in as well as a solar battery charger.  The training center has electricity-- solar one in case you get stuck on a mountain.  Bring convertable REI or similiar brand pants.  At least one if not two pairs.  Duct tape, one gallon zip lock bags, your favorite spice and music are essentials.  You can buy new burned CD's in Port o Prince, Jacmel and Petionville for about 9 to 10 American Dollars.  Bring some money in cash and some in travelers checks.  Be warned though travelers checks are impossible to use unless you open a bank account and you wont do that for the first three months.  Expect to spend some american money while in training.  We ended up spending over $150 US over three months because the "walk around allowance" is what your grandpa gave you when you were five.  Nice for buying lollipops but not much else. You can transfer American money in almost any town any time.  Just ask a language instructor intially and find a safe place with them.  Ok what else.

A battery operated fan.....Archahaie is the hottest area in Haiti.  Its hot dirty and rarely gets cool.
You'll love me if you bring this and give me and atta boy upon meeting me.  Not a dinky hand held one but a nice midsize one.  Also only bring LED flashlights, they have excellent illumination, don't waste energy and are great.  Dont bring self inflatable beds unless you plan on camping and personally after you see what Haiti is like you probable wont want to camp for safety concerns.  Good waterproof light weight boots, Good sandals with minimal foot covering --I bought a really nice pair from REI that covered most of my feet--impossible to keep clean--the dirt here burns and gets into your sandals.  Better to be able to wash off with simple teva's with water proof bottoms.    Bring and empty backpack for all the junk peace corps gives you--language books, manuals, med kits etc.  The backpacks in Haiti cost a dollar and last just as long as you can walk away from the open air market.  Total junk.  You'll need a sunhat but the canvas ones sold in the states are wicked hot and make you want to pass out.  Better to bring a baseball cap and buy a straw one for 20 goudes when you get down here. 
  If you coming in country and have any questions about what you should and shouldnt bring email me and I'll help you out if I can.  We will add more as be get time.