Can you please give me some examples of halachos which we learn specifically from the tagin which, to Moshe Rabbeinu's surprise, Rabbi Akiva added to the Sefer Torah. - I do not know any at all.
Joel Morris, Winnipeg, Canada
Let me point out that Rebbi Akiva did not add anything to the Torah. He learned Halachos from the Tagin that Hash-m had added.
The word "Halachos" includes any type of teaching (e.g. Mussar, Middos). The word "Tag" refers not just to the triple lines on the seven letters "Shatnez Gatz" but to the single lines on the heads of many letters as well (see Gemara Menachos here). The Gemara provides examples of such Derashos for the "Tag" of the Heh and Kuf here and in Shabbos 104a. See also the Midrash known as "Tagi" and "Osiyos d'Rebbi Akiva".