Maria Kalaniemi
Maria Kalaniemi is the queen of Finnish accordion, and a major figure in the Nordic folk revival. She was the first accordionist to obtain a doctorate in accordion at the Sibelius Academy, and is reknowned both as a performer and composer. She is also an excellent vocalist. Her work is inspired by both Finnish and Swedish musical traditions. I have had the privilege of being at a few of her concerts -- that picture on the left is me with Maria after a concert in Sweden. You can read about her latest projects, and check out her concert schedule, at her official web site. For the most part, Kalaniemi plays a "free bass" accordion, which is a rather exotic kind of accordion with a full chromatic layout on the bass side rather than the usual Stradella base. This allows her to get very intricate harmonies and counterpoint into her pieces. It is a rather difficult kind of accordion to play.
Helsingin Kaksirivinaiset This is an accordion ensemble
of five ladies, led by Maria Kalaniemi. It is one of her early efforts.
I don't know if the group was a one-off thing, or if it plays 
on a continuing basis. I hope for the latter,
since they are really good. The title means "Helsinki Two-Row Ladies."
The "Two-Row" refers to the kind of accordion they play. Kalaniemi's
main instrument is a five-row free base accordion, but this ensemble uses
two-row diatonics. Usually these are used for Irish music with a lot of
fast fingerwork, but little chromatic or harmonic interest. This album doesn't
break new ground in terms of the music played, but it is really a revelation
in the use of these two-row beasties. With Irish tuning, the two rows each
have a diatonic scale, but with one row offset by a half tone from the other.
That means that the full chromatic scale is, in principle, available, though
with very odd and inconvenient fingering. Kaksirivinaiset exploit the possibilities
to play all sorts of minor-key nordic favorites, but with a great dynamism
and ensemble feeling. One of my favorites is Kaksi Taunoa, which I have
also heard Norrlåter do up at the Saltoluokta Folkmusikveckan, on
a conventional chromatic with stradella (chord) bass, backed up by the usual
ensemble.
This is a short album, with only five short tracks adding up to an all too brief 15 minutes of happiness. More of this please, ladies! Here is a Youtube video of the Kaksirivinaiset playing Severi Suhosen Jenkka (and here is the great Esa Pakarinen as Severi himself playing it in the great Reino Helismaa flick Rovaniemen Markinoilla. . Or here, as the same character in a 1967 recording, as the same character.. )
Maria Kalaniemi ("Red Album") An album of some of the early classics from the Finnish queen of the accordion. See Maria herself playing Elin Polkka 
Maria Kalaniemi, Iho
Pohjoinen's music
puts me in mind of joik for accordion. Pohjoinen is a remarkably talented
accordionist and composer, playing on what seems to be a free-base accordion
like Kalaniemi. The music on this disk is heavily electronically modified,
but not so much so that the virtuosity or purity of the accordion notes
is lost. I use the word "notes" advisedly, because the entire
album is "constructed" with accordion (except for a small track
using harmonium). This means that Pohjoinen uses his accordion not just
to make sounds in the conventional way, but also as a percussion instrument,
riffling the bellows, clicking keys, tapping the body, and also somehow
achieving an unfathomable bass-drum effect. These noises are accompanied
by Pohjoinens incohate vocal lines, some of which are joik-like chants,
some of which are almost jazzy. All this sounds weird, but it's not a joke,
and it's much more successful than it sounds in description. The music has
to be heard to be believed.