For the Hermits, by Richard Scannell, has a nifty logo
in an unusual vertical shape.
Lately I've been asked the differences between a logo and a header. Most of these questions have come from people applying to the web comic logo gallery at Psychedelic Tree House.
A header is a block at the top of your strip, and is a standard piece of HTML architecture. A logo can go anywhere. A logo may be part of your header, but not the other way around.
A header often includes navigation buttons, like About and FAQ. A logo only includes the title, some art, and perhaps a slogan or decorative words. Sometimes it includes an entire illustration with the strip title and author named.
I am not a fan of putting URLs on logos.
A header is usually rectangular. Logos can be any shape at all. Logos on display may tend to look rectangular because the artist wants them on a certain shade of background, but that is secondary.
Logos look great on t-shirts. Headers look sort of dull, usually. That's because they are intended to be the masthead of what comes below, and not something that stands alone.
Headers often contain information about when the strip updates. Logos don't.
Web pages usually require headers, but not logos. T-shirts like logos, but not headers.
A good logo is your best work. A good header should also be good but can be secondary to your comic.
A good logo should be isolated so that a reviewer can "screen grab" it easily to accompany an article. They don't need permission to do this, as brief excerpts of art may be appropriated for reviews without compromising your rights. If you make it hard to grab the logo, you may lose the review. Hundreds of web comics make this mistake.
The logo should be in an area where no other art protrudes into the logo area, including overlaps. Screen grabs are rectangular, and the logo must be captured without clutter. No reviewer is going to Photoshop your logo to remove incursions.
Collectives often have good logos. Look at the gallery of collective logos to see examples.
Your logo is your brand, but I hate to make you think you should create something slick. In the world of comics, slick logos are usually meant as parody.
Design your logo with art supplies and Photoshop. Don't try to design it with site building tools. Work large at high resolution and reduce it later.
Logos can be replaced. If your first one is so-so, use it until you do a better one, unless you are one of those self-professed lazy people who somehow manage to crank out letters to me, in which you promise to create a logo in the next year or two. That type is a different species from me, and I would not attempt to advise them, beyond suggesting they reconsider their commitment to comics.