What should I do with my blog?
 

My blog (see sig) is a PR4 and gets 4000 unq visitors a month. What can I do to boost my traffic? It's all SE and some small trades. Thanks for any advice.

I guess you could improve blog's design to personalize it a little. You might also consider buying traffic.

I would also recommend you adding icons from feedburner, so the user would subscribe to your blog and you'd see the tendence (you can see example on this blog).

It might help too if you could make more posts on the blog's 1st page encouraging visitor to stay more on your blog.

more traffic doesn't always equals more sales.
What you need to do is to better filter your traffic.
Get a better design so that your visitors will come back and
try to write more sales text instead of just descriptions.