> 1. A company makes a prayer room available for their Muslim employees to do their daily prayers
Services and gifts are from a practical point of view just different forms of bonuses given to employees. A extra room cost money to rent, and if employees are given free time in there then that also cost the company money. The solution is to calculate how much the prayer room cost, divide it per employee that wish to use it, and give each employee that money to do as they wish. The Muslim employees can pool their bonus for the room, and the rest can either pool it together for something else or increase their individual pay check. This way the company do not discriminate and a person who believe in the Church of the Flying Spaghetti Monster has the same benefit and support at the company as a Muslim.
> 2. A company hosts a Women in Tech conference If you have to ask attendees or speakers if they identify as a woman, then what you are doing is explicit discrimination. This is objectionable so simply don't. Organize event instead so that you reaching out to intended minorities by looking at what works and interests those groups.
> 3. A company hosts a GLBT in Tech mixer during Pride Week
Same as #1. If a company spend money on one group, then that is an indirect bonus to those employees who belong to that group. If its not possible to provide every employee the same benefit, at least make the selection process transparent and as fair as possible so both a GLBT mixer as well as a nudist mixer can be created if both exist as groups at the company.
> 4. A social media company creates a couple special features for Black History month (e.g., Twitter's @Blackbirds bot)
Very similar to the above one. Who decide which group deserve the special feature? I would suggest something similar to Wikipedia's featured articles, where any topic can be suggested and a fair process decide which one get selected. The more transparent the better.