I wrote a simple script that came up with all the four-letter combinations using the first letters on a mobile phone keypad without duplicate letters. Most phones that I've seen don't use predictive text in their URL entry screens and the ones that do (Motorolas) do such a bad job, that I'm sure most people turn it off. So I did a search for ".com" domains with the letters "adgjmptw" and no doubles (doubles add a "pause" between letters and makes it harder to type).
Of the 2744 possible combinations I ran through GoDaddy's bulk domain check, only these 348 remain available:
agjw.com agmj.com agtj.com agwj.com ajdg.com ajdp.com ajmt.com ajpj.com ajwg.com ajwp.com ajwt.com amgj.com amjw.com amtj.com apgj.com apjg.com apjt.com atjw.com atwj.com awgj.com awjw.com awmj.com awmw.com awpj.com dapj.com dawj.com dgdw.com dgja.com djda.com djmw.com djtp.com dmpj.com dpaj.com dpgj.com dpgw.com dpja.com dpjd.com dpjw.com dpwp.com dtaj.com dtgj.com dtja.com dtjw.com dtmw.com dwat.com dwgw.com dwjw.com gagj.com gajg.com gajw.com gatj.com gawj.com gdaw.com gdtd.com gjag.com gjaj.com gjap.com gjat.com gjaw.com gjda.com gjdj.com gjdp.com gjdt.com gjdw.com gjga.com gjgp.com gjgt.com gjmj.com gjmp.com gjpa.com gjpj.com gjpw.com gjtd.com gjwa.com gjwm.com gjwp.com gjwt.com gmdj.com gmgj.com gmtw.com gpgj.com gpgw.com gpjg.com gtdp.com gtgj.com gtjg.com gtmj.com gtmw.com gtpj.com gtpw.com gwdj.com gwdp.com gwgj.com gwja.com gwjd.com gwjg.com gwjm.com gwjw.com gwmj.com gwpa.com gwpj.com gwtp.com jadt.com jagj.com jajm.com jajw.com jatj.com jawm.com jdja.com jdjg.com jdmp.com jdwp.com jgad.com jgaj.com jgdt.com jgdw.com jgja.com jgjd.com jgjw.com jgmt.com jgmw.com jgpj.com jgtg.com jgtw.com jgwd.com jgwg.com jgwt.com jmtm.com jmwp.com jpaj.com jpdp.com jpdt.com jpgj.com jpgw.com jpjg.com jpwt.com jtaj.com jtdg.com jtdm.com jtgm.com jtgt.com jtja.com jtmw.com jtpj.com jtpt.com jtpw.com jtwa.com jtwp.com jwaj.com jwaw.com jwgm.com jwgp.com jwjg.com jwmj.com jwmt.com jwpa.com jwpd.com jwpj.com jwpt.com jwtg.com jwtj.com magp.com majg.com majp.com mdaj.com mdaw.com mdjg.com mdjw.com mdmd.com mdpj.com mdtj.com mgaj.com mgdp.com mgdw.com mgja.com mgjp.com mgjw.com mgpj.com mgwm.com mjgm.com mjmw.com mjtw.com mjwg.com mjwm.com mjwt.com mpdw.com mpjg.com mpjw.com mpmw.com mpwj.com mpwt.com mtaj.com mtdj.com mtgw.com mtjd.com mtjt.com mtpw.com mtwj.com mwdj.com mwgj.com mwgm.com mwgw.com mwjg.com mwjm.com mwjw.com mwpd.com mwpj.com mwtd.com mwtj.com pagj.com pagw.com pajg.com pajm.com papj.com pdjd.com pdjg.com pdjw.com pdpj.com pdpw.com pdtw.com pdwj.com pdwm.com pdwp.com pdwt.com pgaj.com pgdj.com pgjp.com pgmj.com pgtj.com pgtw.com pgwj.com pjat.com pjdg.com pjdt.com pjgm.com pjgp.com pjmj.com pjpa.com pjpd.com pjpg.com pjpt.com pjta.com pjtd.com pjtj.com pjtp.com pjtw.com pjwd.com pjwp.com pjwt.com pmgj.com pmjd.com pmjp.com pmjw.com pmpj.com pmwj.com pmwm.com ptmj.com ptpj.com ptwj.com pwaw.com pwdm.com pwgj.com pwja.com pwjd.com pwjg.com pwjm.com pwjp.com pwjt.com pwmj.com pwmp.com pwmw.com pwpj.com pwtd.com pwtj.com pwtw.com tagj.com tajw.com tatj.com tawj.com tdaj.com tdjp.com tdpj.com tdtj.com tdwm.com tgaj.com tgja.com tgjg.com tgjm.com tgjw.com tgmj.com tgmw.com tgtj.com tgwm.com tjdp.com tjtw.com tmgj.com tmgw.com tmjm.com tmtj.com tmwm.com tpaj.com tpgj.com tpja.com tpjm.com tpjw.com tptj.com twgm.com twja.com twjt.com twpj.com twpw.com twtj.com wajw.com wdaw.com wdpj.com wdpt.com wdpw.com wdwa.com wgaj.com wgdp.com wgdw.com wgja.com wgjw.com wgpj.com wgwd.com wjaj.com wjgd.com wjgj.com wjgp.com wjgw.com wjmp.com wjmw.com wjpw.com wjtd.com wjtp.com wmdp.com wmdw.com wmwj.com wmwp.com wpgj.com wpgw.com wpjg.com wpjm.com wpjp.com wpjt.com wpjw.com wtjp.com wtjw.com
The "keypad first letter" domains are very important for mobile services, as the others cause way more clicks on phones. I love my domain "imobs.com" but it's a bitch to type on a keypad: 4 clicks, pause, 9 clicks. Urgh - that's way too much, I want something much slicker with less friction for the end user. Ever wonder why Jamdat is named Jamdat? Take a look at your mobile phone keypad.
By the way, all the three letter .com domains are taken (obviously) and I haven't bothered trying the 5 letter combinations yet as there are 9000+ combinations and the bulk service only takes 500 domains at a time. I'll do that later when I'm procrastinating again.
Now, there's a real option of start an online service with a non-dotCom domain name like .mp as these sorts of domain extensions become more common. I think this is a reasonable decision, and not only because I personally know and like the guys working at Saipan Datacom. DotCom is still the default because that's the easiest for people like my Mom to type into a normal web browser - and in fact, they'll default to www.*.com if you just type in word. But with some basic marketing, I think .mp makes a lot of sense because of the speed at which you can type in the domain and it's brevity in a logo. This is why Nokia/Microsoft's ".mobi" plan is a bad idea, by the way, try typing that in: 9 clicks with a pause between m and o. Bleh.
This is turning into a domain name rant. Everyone knows I'm a domain addict from the mid 90s, but the fact is that any online service starts with a decent domain name. Though this is becoming less important in the world of Google searches ("I'm feeling lucky") and mobile phones where 99% of consumers never, ever, ever, ever, ever, ever, ever type in URLs. But still, you need that handle. You need that way of communicating by voice, simply and clearly what a site is. If you launch a mobile service with a domain like "ReallyCoolMobileService.info" you're really setting yourself up for failure. Not only is it impossible to type, it's impossible to remember, etc.
The best domains are still words or word-like words. Google isn't really a word, but it's pronounceable. That's why there's not much good in the above list. Ooh, I know what I'll do, I'll modify the 5 letter domain search to just domains with consonant-vowel combos and try that. We'll see what I come up with. Anyone know a way of getting "whois" to spit out just a "yes this exists" or "no it's free" so I could just run the script that way? That'd save an awful lot of time.
Update 10/1/04: I'm a moron. I forgot the "d" in my original list. Thanks Juho in my comments for catching the error. I've updated the numbers and the list above. Though I think something is wrong with GoDaddy's Bulk Registration as "magp.com" shows up, and passes their test, but individually it's not available. Here's the full list so you can test yourself.