How many different protein coding genes are in the Human Biome?
The Human Microbiome Project collected samples as shown in the image below from healthy volunteers:



They give an estimate of about 8 Million genes in the human microbiome, which is about 360x the number of genes in the human genome. See here for their press release with a lot of information. Additionally these two articles are as well interesting, if you want to dive deeper into the stuff:


A framework for human microbiome research
Structure, function and diversity of the healthy human microbiome