Look at the browser tab icon, now back to me, now to my Facebook, now back to me, what's in your hand? It's your phone - now it's on my Twitter account.
You will notice consistency in icons, logos and slogans, as well as content. The simple act of making sure your brand identifiers are comprehensively shared across all media is vital in creating brand solidarity. Not only does this create a more professional image no matter the size or weight of your organisation, but gives the user a face for the brand to identify with.
Facebook pages, Blogs, Twitter and most other social medias allow for the inclusion of profile pictures and brief descriptions - make them count! Here is a great article on writing slogans, remember to keep them consistent, but play around with them. If people see your brand on a daily basis, it will keep them guessing and entertained and score you that extra 'share'.
If you aren't sharp with Photoshop and don't have money to spend - look around at what companies with great logos are doing and see if there is a cost effective way to create your own logo after a fashion. Alternatively - find a design student - they will work for peanuts and are usually full of bright ideas, just make sure you don't end up like this:
Unless of course these represent what your company is about, in which case go nuts and expect lawsuits!
Protip: flat, bright colors and simple shapes are IN.