The blog can show the stuff you're learning too. It doesn't just have to be "look at me, I'm awesome." In fact the posts that say "Hey, I ran into a problem and here's how I fixed it" or "Wow, I just figured this out" are very useful to others trying to figure out the same thing.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning