I've been studying whether webcomics that have zero outbound links are hurting themselves.
Following a Rand Corp. survey of 37 leading experts on linking in which the results revealed substantial disagreement, I've been comparing what the men with he blogs say. Some say outbound links have no value, and some say it is a huge mistake not to have them.
Occam's Razor is a fancy name for the idea that the simplest explanation is often the best. There's more to it, but we can dispense with it for today.
Since we have one important fact at our disposal, that Google bases search results on "natural linking" and penalizes schemes to game the system, it would seem that our answer lies in how well having some links versus having no links fits into natural linking.
Because some sites don't link, that's pretty natural. My guess is there is no penalty for not linking. That would be kind of nuts, wouldn't it, for a link based search system?
Because the majority of sites do link, that's presumably "more natural" and likely to be interpreted positively. It is also common for smaller sites to link to some big, authoritative sites in their topic, and a larger number of low rank sites. Linking only to high authority sites is not natural, and might be penalized. We know it's not a great idea, because even people trying to game the system don't do it.
If you've read this far without knowing why links' effect on your search results position matters, take some time to study the words that are turning up in your site results. They appear in your Google Webmaster Tools, in Statistics, under "Top Search Queries." The list can be downloaded.
Note the position in search results.
If your comic is called "Mummies with Catheters," some of the search result words that you'd like to find yourself in are mummy, mummies, mummy catheter, mummy comic, catheters and horror comic. Because of popularity, some of those are going to be difficult, at least until you have a big, well-established comic (mummy) and some may never be possible (catheter). But if your search position for "mummy catheter" is 25, you've got trouble, because you're off the first page of search results and few searches dig deeper. You are going to need to do some text optimizing and image labeling on your comic to move up.
Here is where the link issue arises. By not linking to some "Same subject" sites (some mummy and horror comics) and an authoritative site such as Wikipedia's page explaining catheters, you are not giving Google the hints it needs to organize you into its hierarchies.
I've mentioned before that comics tend to make life difficult for text search engines, because the meaty word are not in fonts -- they are in the masthead, and the comic itself. Search engines can't read that kind of text. People forget to caption their images, and they end up unclassified as images and contributing nothing to the profile of the site.
To me, it seems like adding five or ten outbound links are a great way to cue Google about your intentions.
You should still optimize what text you have by including an "about" pages that uses key descriptive words like mummy, comic, and horror. You should still work in captions by images (Above: A mummy!). You should still use the optional line of tiny copyright text (optional because it is not required to protect your copyright) to include your name, strip title and home URL on every page. (Some say to leave the home page URL off the home page itself. I don't have advice on this yet, but it won't hurt to skip it.)
Look at your analytics, and look how much traffic comes from search engines. How would you like to triple that? A well optimized page can produce strong traffic growth, and I believe carefully chosen links are part of that. Next webcomic you read that lacks links -- send them to this article. If they're still not convinced, I'd love to know why.