I ran 2 blogs... Upto 3 blogs still be fine but more than that, I don't think you can maintain well..
I run only 2-3 blogs in which my personal blog is sucessful due to impressive visitors activity and Google PR
I have 3 blogs. I update one of them about 1-2 times per week. The other two are updated about 1-5 times per month. The first one receives a decent amount of organic traffic from the SEs.
i am new in this line so i have only two blogs now and thinking to increase them in few days according to my budget
2 blogs, plus several content sites. I think I could go with another one, but that would be stretching quite a bit. I'll probably stick with regular sites for the time being.
Personally I have two blogs, i might start one more up. However I really feel that you could be writing the best blog content in the world, with the best layout, and no one would see it. I feel that fewer blogs is better, but you need to promote traffic to them. Spend solid time promoting traffic to it and those few blogs will turn out better than having many with no promotion.
i have 12 blogs and have 4 guys to manage the blogging. Although it is very hard to manage by single person.
Currently I'm running, 4 blogs and 1 forum... but I'm probably going to sell some of the blogs, it's too much work.