List of things missing from .NET

Im always running around missing implementations and id like to know if any of them could be added to TinyCLR while still keeping it tiny.

Or maybe making an official NuGet that contains those implementations so that you can use it per need.
I don’t know how much space that would cost, but i don’t think its too much.

Ill start with the things i needed just today, anyone feel free to add to it.
It just takes too much time to do it properly on your own, so if there is an interest to make it to an official NuGet that would be great.