Favorite online LaTeX editors

Online realtime latex editors
 
http://www.codecogs.com/latex/eqneditor.php can output to gif, or gives HTML or URL, among other options. I especially like the functionality which allows you to use:

http://latex.codecogs.com/gif.latex?[any funcion].

Try for example:

http://latex.codecogs.com/gif.latex?\int_0^\infty e^{-x^2} dx


Oh, wait! www.texify.com offers the same funtionality, and the website is way cleaner!

For example:

http://texify.com/[any latex code]

http://texify.com/?$int_0^\infty e^{-x^2} dx$



Online .xlsx to latex table converter:

I really love this one! Just ddrag and drop your spreadsheet to the following URL, and it provides the code for a latex table:

http://ericwood.org/excel2latex/