Logos are the graphic face of your business. The vast majority of logos are simply text. Understanding the balance between words and font size is important. Understanding the "feeling" a certain font conveys is also important to get maximum effect wanted from your logo. Logo's are part of branding that also includes color selection and other elements.
Besides fonts, there are some times symbols that can also be part of the logo. This is personal preference as there is not a "logo law" that demands a symbol. Many times a company name might lend itself to an iconic shape, or many times even a letter such as the F in facebook, or the G in Google. Something to keep in mind is who is your audience? Also keep in mind that facebook and google have invested millions and millions and have unique places in the marketplace. One reason they can just use a "G" is because of their huge presence in all of our lives. McDonald's golden arches meant nothing to the public when they started out in the 50's, but today are immediately recognized world wide for good and bad. The oval for Ford means something to day that Henry Ford probably couldn't have imagined at the start. Maybe he did for see the day.
I feel companies also can sometimes be too impatient with their logo, as if changing the logo will change their place in the market. GM, IBM, Kodak [if you remember them] and Ford as well as many others have retained the iconic logos throughout the years. People might not know what GMC means, but they recognize that icon collection of letters whenever they see it.
So on to creating your logo. In the following links you will find text-based logos, icon-based logos, and image-based logos as well as a bunch of logos I did not design, but can give you some ideas. If you have an idea, I can quickly and efficiently create the logo you want and need.