Many of my ideas on marketing myself and my books (because you really are marketing yourself) come from JA Konrath's A Newbie's Guide to Publishing. I downloaded it from Kindle for $2.99 so I could access it to my heart's delight.
There are always great tips in Carolyne Howard-Johnson's newsletter, and I love her book The Frugal Book Promotor (and The Frugal Editor). Great advice!
C. Hope Clark's The Shy Writer can especially help if you're not an extrovert. (You may already receive her excellent newsletter Funds for Writers.
Check out other writer's blogs, and even websites. Many of them have sections specifically for writers filled with links, tips and advice. In fact, I will add that to my list of things to do! Update website to include a section for writers. Done.
Some examples are JA Konrath, PD James .... Actually, I found very few authors who did this! If you know of any, send them to me and I'll post them.
What would you put on For Writer's page? Links to writer friendly sites. Markets you've discovered. (Sharing markets will not make you poor! It will make you friends!) Tips. Favorite writing books.
Finally, crawl out of your cave and network with other writers! For an exchange of great ideas both in person and on yahoo lists, look for for writing groups. I belong to Sisters in Crime and Mystery Writers of America (including the local groups) and Public Safety Writers of America. I don't see so many emails from Society of Children's Book Writers and Illustrators, but I definitely plan to join Romance Writers of America. I've heard they are an extremely professional group of guys and gals. That goes on my list, too!
If anyon else has ideas, please share them in the comments!