Having recently visited outside of the country, I always get frustrated about doing things where i can meet locals or do things that are not especially "touristey".
I can imagine what others visiting here must wonder what to do when you are in Nairobi.
1. Buy yourself a cellphone Safaricom/Airtel/Orange/Yu line to keep in touch with your family & friends. Calling using a Kenyan line is cheaper than roaming This are sold all over the town. Unlike places like Dubai where getting a line is almost impossible. Also to dial an international number put + before the international code.
2. Eating out? In the hotel. Most hotels serve your basic buffet which can get a little boring when you are visiting. To check places see here http://www.eatout.co.ke/
3. Other things to do. Some people are not just into going out and having a warm beer at the carnivore. They need to run, jog, swim and other things that make them closer to nature If you are new in Nairobi, you can join many groups that are dedicated to the activities you love. See www.jambonairobi.co.ke.
4. Where to live? A lot of expatriates/visitors to Nairobi always wonder where to live. They end up in overpriced furnished apartments. There are plenty of places to stay in Nairobi. Do your research or use services like www.hassconsult.co.ke
5. You can also organize trips with companies like www.bonfireadventures.com where you can meet Kenyans on the trips and make friends.