A few items worth noting on recent daf yomi pages:
1) Kesubos 60a TD”H M’ma’achan – Tosfos holds that there is an issur of mar’is ayin by issurei derabbanan, but maris ayin b’chadrei chadarim applies only to issurei d’oraysa (perhaps extending the din that far by issurei derabbanan would constitute a gezeirah l’gezeirah). The Rama at the beginning of Hil Basar b’Chalav writes that if a milk-like product made from nuts is served with meat (e.g. non-dairy creamer), the nuts should be left on the table to avoid mar’is ayin (e.g. serve the non-dairy creamer in its container with the pareve label). The Shach (67:6) cites our Tosfos as proof that mar’is ayin still applies even though the Rama is speaking of basar b'chalav derabbanan (uncooked). If I recall correctly the Yerushalmi holds l'halacha that mar’is ayin never applies b’charedi chadarim, but I do not remember the last time this came up – anyone doing the daf yerushalmi remember?
2) Kesubos 61a TD”H Machlifa – Rashi’s opinion (quoted in Shulchan Aruch) is that passing objects, even without touching, is a harchaka. The language of the S.A. seems to indicate that this is not an independent din, but is a concern lest the husband and wife come in contact (e.g. passing a key), but most of the sources I have seen seem to be strict with regards even to large objects (e.g. moving a piece of furniture together).
3) Kesubos 57a RASHI d”h Ha KM”L – Rashi holds that we do not say “eilu v’eilu” if two Amoraim disagree as to what a Tanna. You cannot debate historical facts; “eilu v’eilu” applies only where multiple interpretations are possible.