Inspired by this question.
There are parts of prayer that are not said when praying alone.
Some examples (please add any I missed):
Friday Night: Birchat Me-in Sheva
Shabbos Day before Mussaf: Yekum Purkan, Mi Sheberach
When praying in the synagogue at the scheduled time together with less than 10 people (in other words not enough people showed up to make the Minyan), do you say these prayers or not. Each of those prayers have a communal aspect. Is this considered enough of a community to say the prayers or not?
In a similar vein, the Chabad custom is that an individual says the Shema Prayer, he repeats ani Hashem Elokeichem. When praying with a Minyan, the chazan repeats "Hashem Elokeichem emes". When leading a service with less than 10 men, how does the chazan finish off the Shema? This same question would apply to congregations who have the custom to say "kel melech neeman" before Sh'ma if praying alone whereas the chazan repeats "Hashem elokechem emes" when praying with a minyan.