Oh boy, do I have a treat for you. Try saving the following as `input.md`:
# Hello *world*
## Math
$$x = 2 \cdot y^3$$
- foo
- bar
- baz
1. Yes
2. No
3. Maybe
---
Right Left Center Default
------- ------ ---------- -------
12 12 12 12
123 123 123 123
1 1 1 1
Table: Demonstration of simple table syntax.
pandoc -t html input.md | xclip -selection clipboard -t 'text/html'
Gdocs would then really only need to support the same semantics with underscores, asterisks, octothorpe heading levels and title sizes.