Rain a' fall

Moving along down the list, I see Shane has added some good advice for men and thier pants. Starting with the poncho/rainsuit, don't bother. Jamaicans are very anti-rain and aren't likely to be walking around in it, even if it's an emergency. When they are walking around, they are using an umbrella. As a PCV you can buy umbrellas anywhere but if you are coming in perhaps you should bring a small one, high quality, just in case it's raining in the first few days. Save space and skip the poncho.
Next on to the beach towel. I see where they were going with this but it's a little misplaced. Think about how difficult it will be to hand-wash a beach towel, think about doing it every week. A better solution is to bring a couple quick dry towels that are made by hiking companies. These are much easier to wash and you can pack two in the space of one beach towel. Plus you can travel with them when you go on weekends to other PCVs or the beach.
Toiletries are an interesting issue. It just depends on what you like. Khaled and I really like Tom's of Maine toothpaste, so we brought a bunch. If you have no preference, just bring enough to get you through training. Be sure to pack extra razor blades if you use a Mach3 or something like that. Ditto for any kind of special tampons/pads you use. Remember, you can get anything you need in Jamaica, it just won't be the stuff you like or are used to. Take shampoo, which is sold in hundreds of varieties in the states, is very limited here. In the country, where we live, our supermarket carries VO5, Suave and a local brand called Lasco. Thats it for shampoo, no herbal essences here, unless you pay big money in the city for it.
For kitchen items, I wouldn't reccommend a lot of tupperware or things like that. Really what I found myself wanting was a decent vegetable peeler, a rubber spatula and a good travel mug for my morning coffee. You can get tupperware, pots and pans here. It's those little things that make life easier that you will be wanting.
More on the miscellaneous items later.
But you really will need a battery operated am/fm radio. It's on the consolidation list.