How long are you planning to be there for? Typically the best thing you can do to be helpful is to go and be a (responsible) tourist there--spend money. Sorry, I know it's not what you had in mind.
What is your area of expertise in nursing? You may be able to find a small group that travels to the area regularly (yearly, for instance), has connections there, knows the needs, and goes for a specific purpose (such as fixing cleft palates).
If you want something different from the "standard" tourist experience, look for some kind of "fair trade" style of tourism... something with a homestay in a rural area, for instance; cooking and craft classes can also be a good way to see something a little different and put more money in the hands of people who need it. These types of experiences also help make it possible for those who prefer it to continue living a traditional lifestyle.
Take a very nice first aid kit with you and you may run across someone who needs a bad cut washed and dressed--it may seem small-time, but it can make a difference for that person. No matter where I go, when people find out I'm a nurse they start asking me for help with things like that--first aid, assessment, and advice.
There's an organization called Stuff Your Rucksack that gives specific advice/takes particular requests on what supplies an area might need. As tourists/travelers we are almost always completely wrong about what the community needs, or where to offer our donations in any case. I have not used this organization so I can't vouch for it, but I will be considering it in the future. I'm not sure how extensive it is at this time. If you want to bring some materials/supplies, you could consider finding a mission, orphanage, co-op, etc run by foreigners (just to make communication easier... these are the orgs more likely to have websites), tell them you're coming, and ask what you can bring.
While I was always a little skeptical about short-term volunteering and had read the same kinds of opinions you have, being in the developing world as a longish-term volunteer has really opened my eyes to the reality. Some volunteers are good and some are bad, but it's never quite as simple as it seems from the outside, and almost never will anyone tell you you're NOT welcome, whether they really want you or not. People proudly come home and tell stories about how the locals had tears in their eyes when they accepted the volunteer's gifts or services--but that's never the whole story.
Again, I'm sorry to pour cold water on the idea, I know you just want to help. But (outside of a humanitarian emergency like a natural disaster), spending money and possibly bringing items is probably the most realistic way of helping for a short-term visitor... IMHO.