I wrote an editorial that was published today on Building Better Communication Skills and it talks about the need to improve your communication skills. Specifically I talk about writing, since that is the type of communication that we seem to do the most often.
I recommend blogging as a way to improve your skills. To me, blogging is a no-brainer, and it's easy. It can take some time and effort, but you don't have to feel pressured to get it done at a particular time. I'd recommend that you do it at least every other week, but when you write inside that two weeks is up to you. You can do it late at night, you can do it on the weekends, at lunch, and even in a bunch of separate sessions. Unlike something like Toastmasters, you have more flexibility.
I have a whole set of posts on blogging, with different ideas and techniques. I would urge you to consider setting up a blog and working on improving your writing skills. You'll use them often in your career, and being able to clearly express your opinions, thoughts, and knowledge, is very important to growing your career.