Is there anything like LaTeXit, a Mac-only program, that converts math equations into LaTeX code, for windows?
You should try EqualX. It seems to work very well. The only bad thing is you can drag and drop, you need to copy paste.
the best Windows editor for LaTeX/Tex is LyX
If you use chrome, there is an extension that LaTeXifies https://chrome.google.com/webstore/detail/dinfmiceliiomokeofbocegmacmagjhe
Update: Daum editor requires Adobe Flash which is no longer supported by Chrome and Edge is also phasing out.