Are there any good Jewish Blogs about the Modern Hebrew language?
Best is a matter of taste, but here are a few that you might enjoy:
http://blog.tapuz.co.il/einat3 - modern hebrew
http://www.thmrsite.com/?page_id=6 - Hebrew (and Farsi, linguistics, etc.)
http://hebrewlog.blogspot.com/ - modern hebrew
http://yitzhakavinery.wordpress.com/ - About Yitzchak Avinery who was a Hebrew language scholar and inventor of Hebrew words, an Avshalom Kor of his day
http://haharoni.wordpress.com/ - modern Hebrew (also other subjects)
http://www.dorbanot.com/ - modern Hebrew, slang
http://hasagot.wordpress.com/ - blog about mistakes, interesting findings in the classic Even Shoshan Hebrew dictionary (very niche audience!)
http://benyehuda.org/blog/ - blog discussing classic Hebrew literature
http://www.icast.co.il/default.aspx?p=Podcast&id=363234 - podcast for Avraham Kor, a guru of the Hebrew language popular in Israel
http://www.youtube.com/view_play_list?p=3270207030CC172E - YouTube videos of short clips explaining interesting aspects of the Hebrew language by Avraham Kor
** http://www.safa-ivrit.org/ **- not written in a blog format, rather an article format, but still very interesting insights into the Hebrew language, very popular among Hebrew enthusiasts
http://hebrew-academy.huji.ac.il/Pages/default.aspx - homepage for the National Academy for Hebrew Language
Unfortunately, balashon is the only serious blog about Hebrew written in English that I could find.
Not a blog as such, but a resource centre for those learning modern Hebrew: http://www.hebrew.ecott.ch