Your logo and tag line are also good candidates for trademarks. The first litmus test: Is it unique? What makes a logo unique is the combination of the symbol with the company name, their spatial relationship and the logo's colors. If your tag line is a unique phrase, it can also be trademarked. Hallmark's "When you care enough to send the very best" connects a Hallmark brand attribute -- quality -- to its product. This tagline helps distinguish the Hallmark brand.
The Trademark Process
It's not necessarily expensive to trademark something. In the United States, whoever establishes priority in a mark is usually considered the owner of it. In other words, if you're the first company to use a unique mark to identify your products or services, you don't need to register your mark to gain rights to it. You must, however, add the trademark symbol, TM, to the mark you're claiming rights to. It's still not quite a substitute to registering a mark through the U.S. Patent and Trademark Office, which establishes ownership beyond a doubt.
Of course, all of this is dependent on the "uniqueness" of your mark. The Internet is a good source for starting your trademark search. Visit free Web sites that display existing trademarks, like those maintained by USPTO, Secretaries of State or Yellow Pages online. Or, for a fee, go through an online trademark search company. You can also hire a private company or attorney to conduct detailed searches that include misspellings and alternate spellings. It's best to seek an attorney who specializes in intellectual property law.