What URL's characteristics have a real impact on the UX?

Question

I'm starting a blog soon so I've been thinking about what I should take into account when choosing an URL.

Some variables I've thought about: Length, meaning, suffix, memorability, SEO. Related to these my thoughts:

• Without considering other variables: "the shorther the better". One reason is to prevent typing errors. Although I don't think it makes a big difference unless long means really long.
• Short URLs without meaning < longer ones with meaning. (xkcd|4| seems less memorable than codinghorror|12| or elithecomputerguy|17| )
• If both short and long URLs provide the same meaning, again: "the shorter the better".
• .com seems to be "the default" suffix in users' minds. I can't find a really good reason to add .com.otherSuffix if you have the chance to go just with the .com .
• Positive/negative implications of similar words cointained in the URL. (e.g.: godeth)
• A lot of people use a search engine to get to your page so the most searchable the better.

So, what characteristics of the URLs affect UX and which of them are the most relevant?

Any research on the topic would be very useful.

Answer 1

The only reference to research which I found was on the site usability.gov which did some research on optimal url names for government organization. To quote the article

When the General Services Administration (GSA) changed the names of the U.S. government's official Web portals from FirstGov.gov to USA.gov and FirstGov en español.gov to GobiernoUSA.gov, we researched domain name options and usable domain name characteristics. The strategies for selecting domain names discussed in this article apply to top-level domain names, not to all types of URLs.

Ten Characteristics of Usable Domain Names Between our research and experience at GSA, we uncovered 10 characteristics of usable domain names that help to increase trust. The most usable domain names are:

• short (12 characters or less)
• guessable
• easy to spell
• easy to type
• easy to say and pronounce memorable
• meaningful to customers
• meaningful to Web site partners
• meaningful in the intended language
• run together without punctuation, if compound words (e.g., GobiernoUSA.gov)

The same article also states the name can cause confusion about the objective of the site if not chosen carefully. To quote the same article

FirstGov.gov had never been a popular name for the official portal of the U.S. government. It was redundant and awkward to say. In fact, GSA conducted several focus groups and learned that many members of the public thought FirstGov.gov referred to a bank or an insurance company, despite the .gov suffix. Some government agencies were hesitant to provide the required link on their homepages because the name didn't mean anything to their customers. In addition, Web logs showed that thousands of people were already typing "USA.gov" into their browsers, guessing at what the name should be.

Lastly if your planning to be in a specific language, then your blog url should be something that makes sense in that language. To quote the same article

The name originally chosen for the Spanish-language site also had issues; it was a hybrid-language name. "FirstGov en español" did not describe the site from a Spanish-speaking point of view. "Español" means "Spanish" but "FirstGov" has no meaning in the Spanish language. In September 2006, GSA conducted an online survey of Spanish speakers in the U.S. to test five possible names for the Spanish portal. GobiernoUSA.gov was the clear favorite because "gobierno" means "government" in Spanish.

Another good reference is Neilson's article on the URL as a UI