What is a word for a person who loves to share knowledge? So far I have educator in mind. Is there any other word?
How about "maven"? According to the Wikipedia article,
A maven (also mavin) is a trusted expert in a particular field, who seeks to pass knowledge on to others.
[Admittedly, many dictionaries define the word merely as something like "an expert", but the meaning is in flux, and the "person who loves to share knowledge" meaning is getting more common.]
A pedagogue likes to teach others things.
A few more words for people who share knowledge: teacher, "teaching assistant", tutor, mentor, coach, guru, contributor, author, polyglot, blogger, Wikipedian, ...
How about "pundit"? A pundit is
a person who knows a lot about a particular subject and who often talks about it in public
In addition to the excellent answers previously given with positive connotations, I offer this pejorative one:
...because loving to share your knowledge doesn't always mean others love to receive it.
That's not intended as a subtle dig at StackExchange users. I just really like the word.
Within religion and technology people who are keen to spread ideas are know as evangelists.
For evangelists who are promoting knowledge of a certain type of technology or religion, spreading the 'word' is seen as it's own reward, rather than seeking any monetary reward.
A professor is someone who professes his knowledge or faith, gratuitously, sometimes. To all who would listen.
A fountainhead is a person who is a source of all kinds of knowledge. S/he may not love sharing that knowledge, however.
On the other hand, why would a fountainhead deliberately dam up the works by refusing to share knowledge? Besides, isn't the job of a literal fountainhead to benefit all the people who congregate around it? How could a fountainhead of knowledge not love benefitting others?
Yeah, fountainhead is an apt word to describe someone who loves sharing knowledge.