They’re just small jpg files that can really spice up your blog site.  I’m not sure if there are online sites selling comic strips for this purpose, but if you know anyone like a graphics artists or cartoon artist, have them create a cartoon strip for you, scan it, or compose it in any image editing software, and post it as a conspicuous part of your website or blog site.  Humor is always a welcome feature in anything.

Just make sure, it’s really funny and update it regularly especially if it’s a series.  Your blog visitors will love you for it.  Nothing beats a funny strip or even a joke that can make your visitors laugh when they visit your blog.  Try it.