Medecins Sans Frontieres (MSF), a.k.a. Doctors Without Borders, on the ground in Burma and China (amongst numerous other countries/projects).
They had an existing presence in Burma and thus have been on the ground in Burma since day one of the cyclone tragedy. The Junta denied access to aid organisations, and I believe, are continuing to deny access.
MSF have 12 mobile medical teams in play, and are also distributing food. 90 staff on the ground, half medical.
Also deploying teams for the China earthquake disaster.
Can donate here.
More about MSF and their excellent work here.
While I'm on the topic of good folk doing great work, see also the Fred Hollows Foundation: $25 restores sight in a person, which often results in relief for an entire family (e.g. children who are taken out of school to care for the disabled family member, and the rest of the family). Fred Hollows was a great man. His foundation, founded by his wife, does brilliant work.