Curiad A wide range of vocal, instrumental, choral and orchestral music, including the very popular tenor solo Llanrwst - which you can actually listen to on Curiad's excellent website.
Gwynn Publishing CompanyVocal and choral pieces, notably Cadwyn, a cycle of folk-song settings for SATB which is very popular indeed, and New Star, a cantata in the style of a musical telling the Christmas story - perfect for secondary schools, and involving singers of all ages and abilities - even those lads from year 10!
Spartan Press Instrumental music, including Star Turn for a wide variety of solo brass instruments, and Pianimals,, a piano piece in which Crow is played on the black keys only (and by the left hand only); Polar Bear is on the white keys, and Zebra is... well, give Spartan's far-from-spartan website a visit, to find out!
AdlaisHarp music, in particular Triban, a substantial three-movement piece which has been played in recitals by some great harpists such as Sioned Williams. Adlais don't have a website as yet; their address is Adlais, PO Box 28, Abergavenny, Gwent, Wales NP7 5YJ.
LlonnodThis is my own company, which also publishes a great deal of music, mostly choral.