In an economy like this one, your best career survival tip may be to hold on to the job you've got. If you're working at a company that isn't necessarily shutting its doors, but may need to let some people go ... your challenge is to prove yourself too valuable to let go. Social media (blogs, social networks, forums, online video, etc.) can help with this. Here are a few ideas for how you could use social media to keep the job you have right now:

1. Grow your personal brand. Having a strong personal brand gives you something to stand for. It builds your reputation. It's not about blogging or any one thing. Your personal brand means having a way of describing yourself and then using tools online such as social media to bring it to life. You may choose to start a blog, or build an online profile, or start actively using Twitter. Regardless of what you choose, start building brand "you" right now.
2. Be an accidental spokesperson. An "accidental spokesperson" is someone who begins to speak for a brand even though they have not officially been designated as a spokesperson. Being an employee of a company, you may need to tread carefully with this advice, as I am certainly not telling you to go out with social media and portray yourself as a spokesperson for the company you work for if you are not authorized to do so. Still, if you are in a sales role - start talking about sales and joining communities for sales people. Simply by nature of your experience, you will start to be seen as a representative of the brand you work for.
3. Invite testimonials. With most social media, there is the potential for two way interaction. This means that you can and should invite comments from people who interact with you. This could come in the form of a tweet on Twitter from a customer happy with your service, or a client posting a comment on your blog. Depending on what is appropriate with your particular role, you need to find ways to invite people to share these testimonials visibly. And then you need to share them with your boss to make sure he or she sees them.
4. Network internally. Many organizations have Facebook pages or LinkedIn groups. As an employee, you should find where those are and join as many as you can. Social media gives you the chance to network with your colleagues and others that may work at your company but that you haven't met before. Connecting with them not only gives you a sense of belonging and purpose - it can also create opportunities within the company for you to get involved in more.
5. Join or start the social media team. As more and more organizations start to figure out how to use social media strategically, there is very often a task force or internal group appointed to figure it out. Regardless of your role, sometimes the main qualification to be part of this team (or to start one if none exists) is a passion for social media. Take your passion/interest in social media and put it to use. How do I know you have this passion? Well, you're reading a blog right now, aren't you?
6. Go beyond your job. One thing reading or writing blogs, participating in social networks or using new social media tools offers you is the chance to go beyond what may be described as your job. For example, you may not be responsible for customer service, but if you read about someone in your social circle that had an isue with your product and you can help them resolve it - you should. Social media allows you to be a real person and add more value to the place you work beyond performing the bullet points that are on your actual job description.