I have my own answer, however, here I got a really enlighten answer for the question you keep asking me. I hope this answer would find you well.
Actually, I embed this from Quora (seems like I am drowning in this kind of social networking!) for that question and this answer from Nikhil Garg was awesome and being highly voted up by Quora.
- Enhanced expression: regularly writing about my thoughts and mental condition has made it easier for me to express and articulate whatever is on my mind.
- Stronger grip over language: regularly blogging has made me more conscious of sentence structures, readability, and general grammar. I used to be terrible with spellings (and I still am) but thanks to spell-checker of the blogger, I'm in a much better state now. My vocabulary has improved too.
- Introspection: if I'm putting my thoughts out on a blog for the whole world to read, I've to be extra cautious and be really sure about what's on my mind. Further, I don't edit my posts after writing them so whatever is written once is etched in stone. It makes me think deeper and I often realize why exactly something makes me sad or happy.
- Time machine: reading old posts is the best way of going back in time and reliving past experiences.
- Big picture: I have trapped my mental state across time on my blog. Looking at all the posts gives me a big picture - how my thoughts have evolved over time. How my desires, ambitions and insecurities have changed and how they have not changed (yet). In my opinion, this is the most important benefit of maintaining a diary type blog.
- Socializing: the network of bloggers is very dense and bonds are rather strong. I've met some incredible people through my blog who have gone on to become special friends in real life. Since these people follow my blog and I follow theirs, we know and understand each other very well.