Great news for safari tourists - there is a three-country visa!
KENYA, RWANDA and UGANDA have banded together and launched an "EAST AFRICA TOURIST VISA" valid for multiple entries for all three countries.
The visas cost only $110., which is far cheaper than buying all three (or even two) individually. The visa is valid for up to 90 days and is good for multiple entries of the three countries during those three months.
Right now only Kenya and Rwanda are issuing these visas. You must get the EATV from the country of first arrival. If you are flying from Europe to Nairobi then you would apply for the EATV through Kenya.
Be warned, Tanzania is not part of this group and requires a Tanzanian visa for any entry.
Also, if you have an EATV and go to Tanzania, your visa becomes invalid and you will need another Kenyan visa to re-entry Kenya for a flight home out of Nairobi airport. This may be sold and issued at the border as you drive from Tanzania to Kenya. The full details are not yet available.
Click here for East Africa Tourist Visas.