Scheidemann was a direct student of Jan Pieterszoon Sweelinck from Amsterdam and worked for a long time at Katharinenkirche in Hamburg (the same church were after his death Johann Adam Reicken took over the position and J.S.Bach visited him at least twice).
Scheidemann was probably one of the two most influential north German organists/composers/improvisers at the middle of the 17th century Hanseatic city of Hamburg (the other being Matthias Weckmann).
His music was considered "sweet" by the contemporaries in contrast with the "serious" style of Jacob Praetorius II. He left a large body of organ works - praeambules, toccatas, fugues, fantasias, canzonas, chorale verses, chorale fantasias, and a set of amazing 8 Magnificat cycles (on each of the psalm tone).
By the way, the Swedish organist Karin Nelson proposed in her dissertation that these Magnificats were used in teaching improvisation during Scheidemann's style. I couldn't agree more - these settings indeed can even serve as models for our improvisations because Scheidemann employs such a huge variety of contrapuntal styles and techniques in each of them.
In 2012, I played two full concerts featuring these Magnificats at Vilnius University St. John's church as part of my ongoing monthly cycle of concerts "Seven Centuries of Organ Music". It was a little too early to start celebrate his anniversary but I couldn't wait - I literally fell in love with his music a long time ago - at Gothenburg International Organ Academy in 2000 where they were inaugurating the newly built 4 manual North German style organ in Orgryte New church.
But yesterday I played a full recital of Scheidemann's music at my church - a nice mix of most of his organ genres, everything arranged according to the keys (or modes) d, C, e, G, g, and F.
I hope you will enjoy his Magnificat Primi Toni from last year's concert and Praeambulum in e (performed at the church of the Holy Cross in Vilnius last Friday during church service where I substituted for a friend).
So if you like Scheidemann's music, I invite you to think about how you could celebrate his anniversary before this year is over. One of the obvious choices would be perhaps to play a few of his pieces for a church service since there is not much time to prepare for the full recital. You could also learn one or two pieces, or record a video or two and post them to YouTube.