The Mishnah Berurah sometimes quotes a sefer Shulchan Shlomo (e.g. 489:3 that women should not count sefiras haomer with a beracha since they will inevitably forget a day). Does anyone know who the author of this sefer Shulchan Shlomo is (it cannot be R' Shlomo Zalman Auerbach (though he authored a book of that name) as he lived after the Chofetz Chaim) and/or where a copy of the sefer can be found?
The author of this Sefer Shulchan Shlomo was Rav Shlomo Zalman Mirkes zt"l. He was the chief rabbi/av beis din of Mir in the mid 1700s. The sefer is quoted approximately 80 times in the משנה ברורה, ביאור הלכה, שער הציון.
I just noticed that there is now a very informative (Hebrew) article about him in HaMichlol (nothing yet on Wikipedia) with good links to check out.
Some brief additional info about him can be seen at the bottom of this answer re: the history of the Mir yeshiva (and earlier yeshivos there).
After leaving Mir in the late 1760s, Rav Mirkes moved to Koenigsberg (now known as Kaliningrad) where he passed away and was buried in the old Jewish cemetery there close to the kever of the Baal HaPardes, Rav Aryeh Leib Epstein. Also buried in that cemetery were the authors of the Pischei Teshuva, Be'er Heitev and HaKsav VeHaKabalah. Sadly, that old Jewish cemetery in the Tragheim section of Koenigsberg was built upon and now sits underneath a playground. See approximate location here.
If you can handle the German, there is an old volume published by the chevra kadisha of Koenigsberg listing who is buried there.
There is an online shiur that deals with the author of that sefer. It is the class dated June 15. http://www.webyeshiva.org/course/the-mishna-berura-and-its-sources/