COOO.OOO is simple, beautiful, and symmetrical. It barely looks like a domain and it sounds like a call. And it's easy to recall. The C is similar to the O and creates a slight visual hiccup. It's as if the C started life as an O and shunted right, partially slipping under the next letter. The C is a cap or endpiece, fixing the slippery Os, creating the impression of a word, and sending the eyes skittering right, giving direction to what might otherwise be staring, triple eyes. I love domain names and I love wordplay. And C is my middle initial (well, one of them, anyway). And C is pronounced, "see". So you might pronounce the name "see oooooo" as in "see you" or "see who" as well as "koooooo", as in "come here" or "look at me". COOO.OOO is reasonably easy to say over the phone (C, triple O, dot, triple O), but its main virtue is visual strength, which is very rare for a domain name. Most domains are mentally processed as words, not pictures.
Most people aren't the least bit interested in domain names. They recognise important ones and, at some level, they might notice when the domain in the browser bar matches the website, giving it some heft and credibility. But that's about it. They don't like typing them. And they can misspell them and go careening off into dark and dangerous thickets. Sometimes, though, you might need to tell someone a domain, and that's a problem if it's difficult to spell or too long. So the best thing, in my view, is to have a nice (possibly quite long) authoritative and descriptive name that appears in the browser, and a short domain that you can say over the phone which redirects the listener to the main one. For example, I have russellkightley.com, which is my author site (fistname+lastname.com is the recommended domain for writers). Once someone's there they see a .com that matches my name, and so, subliminally, they're reassured. But it's a nightmare for anyone to spell. And it's quite long. So I use RCJK.me to point to it. They're my initials. The domain is short and easy to dictate over the phone.
My business name is Russell Kightley Media and my ancient site is RKM.com.au. I chose Media because it's wide-ranging (I was working on medical videos at the time) but also because its contraction is RKmedia, which sounds like archimedia (as in Archimedes). And so the logo is an RK mapped onto a sphere that sits snugly inside its cylinder. Archimedes was so proud of his discovery that the surface area of a sphere is the same as the area of the enclosing cylinder that he wanted the figure inscribed on his gravestone. I wanted the .com but it was taken, but I do have rkmedia.net. And for several years (many years ago) I hosted other websites under that domain (making the .net more relevant). Here are some animations of the sphere-cylinder relationship (notice my Archimedian logo in the corner):
Fiction.Red points to the fiction books in my shop. It's a play on words, too, as in "fiction (I've) read". Once you're there, you'll see that the URL in the browser: https://shop.russellkightley.com/collection/fiction tells the visitor that it's a shop (subdomain) belonging to Russell Kightley (and that he managed to get a .com) and it's the collection of fiction. So, easy to remember and get there, and once there you're (hopefully) reassured that it's all legitimate and that the URL tells you something useful. Obviously, the site's secure (https:// with a little padlock). If you're trying to sell something, you must have a secure https (SSL) and your domain should look authoritative.
Scientific.Pictures is my scientific illustration and animation site. All pretty self-explanatory. I've tried to carry the scientific pictures theme through all titles and links so that the visitor has a sense of continuity. Like Fiction.Red, the whole domain is descriptive (there's no meaningless .com at the end, for example).
Scientific.Graphics (sister domain to Scientific.Pictures) points to my print shop. Graphics meaning, amongst other things, printing. I use it all the time myself as a shortcut to that site.
kindly.contact points to my contact page. It's a gentle call to action that works well in email footers and on social media sites.
BEST DOMAINS. Almost everyone thinks that a .com is the best domain extension. In most cases, I agree. But for descriptive two-word domains (like scientific.pictures) the dot neatly separates the two words and there's no .com hanging off the end. It's shorter, cleaner, and easier to read.
DOMAIN SYMMETRY. Symmetry is rare in domain names. Domains are generally chosen for meaningful words or initials or acronyms. Sometimes, there's wordplay or domain hacks (such as the famous me.me that spells meme, or who.is). But there's not much effort (as far as I know) to secure symmetrical domains. COOO.OOO is symmetrical from top to bottom if you ignore the dot:
COOO.OOO . And there are three Os on either side of that dot (I wanted one with three Os to the left of the dot). So it's pleasingly balanced, more so if I add a triple-O subdomain: OOO.COOO.OOO... I could also create a sense of movement with COOOO.COOO.ooo (looks like a locomotive) or a progression with COOOOO.COOOO.COOO.OOO. Of course, the most perfectly symmetrical domains would be OOO.OOO (reserved by the registry) and XXX.XXX (taken). XXX.OOO is also reserved by the registry.
My other domain chosen for its simplicity, beauty, and symmetry is VOOO.OOO. This one is more symmetrical about a vertical axis (you can rotate about the V), but it still has the pleasingly balanced triple-Os. The V is dynamic and powerful, suggesting vehicles or velocity (c is the symbol for the speed of light, or celeritas, so cooo.ooo is also a very fast domain). V suggests visual, especially when combined with the staring, triple eyes. V is also shorthand for vegan, and the Os echo the staring, pleading eyes of the animals. It's a powerful domain, however you look at it. Or however it looks at you.
COOO.OOO and VOOO.OOO are not words and they're not numbers (but six Os make a million). They're closer to shapes and they appeal to the designer in me. I simply find them beautiful.