J is the awkward one. It is worth 8 points like the X, but it has only a single two-letter word to its name and it sits at the front of nearly everything else, which means it needs a free square with room to its right. A J is genuinely worth playing early, because the position that accommodates it may not exist later.
Jo, and why it matters
Jo — a Scottish word for a sweetheart — is the only two-letter J word in this dictionary, and it is the single most useful entry on this page. It is what lets you unload a J parallel to an existing word instead of waiting for an open row. Note that this dictionary does not carry jos as a plural, so it is a two-letter play only.
J at the end
Three words finish with a J rather than start with one: haj, raj and taj. They are worth remembering for exactly the reason jo is — they fit board positions the front-loaded words cannot reach, such as a bonus square at the end of a run.
The rest
The three-letter list is mostly familiar: jab, jam, jar, jaw, jet, job, jog, jot, joy, jug, jut. The ones people miss are jee, jeu, jin, jow and jus — all legal, and all handy when the obvious play is blocked.
The complete list
2 letters (1)
jo
3 letters (26)
haj jab jag jam jar jaw jay jee jet jeu jew jib jig jin job joe jog jot jow joy jug jun jus jut raj taj
4 letters (98)
ajar ajee djin dojo fuji hadj haji hajj jabs jack jade jagg jags jail jake jamb jams jane jape jarl jars jato jauk jaup java jaws jays jazz jean jeed jeep jeer jees jeez jefe jehu jell jeon jerk jess jest jete jets jeux jews jiao jibb jibe jibs jiff jigs jill jilt jimp jink jinn jins jinx jism jive jobs jock joes joey jogs john join joke joky jole jolt josh joss jota jots jouk jowl jows joys juba jube judo juga jugs juju juke jump junk jupe jura jury just jute juts mojo puja raja soja