I registered SneakyDave as a word mark about 12 years ago, it is now listed as "abandoned" for some reason. At the time, it only cost $250 and a little conversion with a legal person about what to categorize the term as.
I probably wouldn't do it unless you're really vain (the only real reason I did it), or until your site is popular enough that it requires it. It may make more sense to create an LLC for your site itself if you plan to create a business venture out of it, just to protect yourself personally. But I'm not a legal expert.
If you ever have something really crucial towards copyright and being your intellectual property, and want to disclose it online, you first enclose the works within an envelope, send it to yourself via your countries mail system, and never open it. That way you have your countries postal stamp dated onto the sealed work before you have published it, and that holds up in a court with more authority than an argument over dates published.
That is one cheap method lawyers will tell you to use if you don't want to go through intellectual property costs and such, ie. a new startup fits the profile.