Looking at this question, I wonder what good and useful web services are out there. For example the LaTeX symbol classifier looks interesting. You can draw a symbol with your mouse and get back the LaTeX name of that symbol (the software analyzes your drawing). There are many others out there. Which one do you use regularly? Please provide a link and a short description.
mathurl You input a formula in a box and get an instantaneous render (as png) which you can then shorten and embed. They support amsmath and have shortcuts on the side for common symbols, operators, font styles etc. Great for tossing in an equation or two in an email or forum post on the fly.
This web app seems fairly new and does a good job of recognizing hand-written equations. It works on iPhone or iPad so you can draw equations better than with a mouse. In return, it provides an image of the equation and the LaTeX or MathML code: http://webdemo.visionobjects.com/equation.html
http://uniquation.com is a math search engine that indexes and searches formulas represented in a tex format.
http://docs.latexlab.org/ supports full LaTeX inside Google Docs with realtime PDF preview.
A collaborative LaTeX writing environment: https://www.sharelatex.com/
OverLeaf (renamed from WriteLaTeX) is another option: https://www.overleaf.com/
At Scribtex you and collaborators can edit and compile latex files. With the free version you can have three projects with one collaborator per project. For more you have to pay.
My go-to-web favourite is this nice little Online LaTeX Equation Editor for making the business of assembling complex math LaTeX code a complete non-brainer. The interface is very intuitive and the online preview makes it easy to immediately see what's going right and wrong. Its preview function extends its usefulness well beyond the TeX domain. You can select a good range of display options (typeface, font size, colour, transparency, dpi, etc.), then download its output in one of a number of formats (gif, png, pdf, etc.) for those times you or non-TeX others might want to embed LaTeX-typeset formulae into non-TeX applications.
This service allows classification by drawing (even works on mobile devices!) and by text search:
Disclaimer: I am the author of the service.
The handwriting recognition toolkit (
hwrt) is one possibility to classify you recordings. There are still many rough edges and the software gets updated on a daily basis (11.06.2015). The user interface is in a browser and looks like this:
The installation is explained in the documentation. If you have trouble or have an idea how to improve it, just leave a comment or write an email (firstname.lastname@example.org).
This is a part of my bachelor's thesis. The thesis, some presentations and links to all software projects are on http://martin-thoma.com/write-math/
Google Docs supports LaTeX equations.