Syntax highlighting code is an important customization one should consider whenever it comes to publishing useful code on the web, something which my friends also recommended me to do when I posted code in this blog. But on the web when I searched for syntax highlighters I couldn't get what I exactly wanted with the keywords "Syntax Highlighting", "Python Syntax Highlighting", "Java Syntax Highlighting", etc, to be fair with Google its not that it didn't produce results, but not the generic results which I was expecting, but finally managed to break the ice with some sensible searches like "Online Syntax Highlighting", "Syntax Highlighters", etc.
One thing to note is that the more specific your keywords are, the more accurate the results will be, otherwise its really hard to get what you want, for example, see the difference between the searches "Syntax Highlighting", "Code Syntax Highlighting" and "Online Syntax Highlighting", clearly the third one will give you the result you want immediately. So its my duty to recommend and share the bits and pieces which I collected from web for syntax highlighting code, just to save you some search work, especially if you want to get the highlighted code, the way you want it to be. If you have time only to paste your source code and need to get HTML source/output for syntax highlighted code, then the below are my favorites (although its not complete, its enough for us to get the job done).
1. www.tohtml.com - The first useful result I got and the one I use mostly for my code highlighting purposes, the good thing I like is the default white background with very suitable colors for language keywords.
2. http://qbnz.com/highlighter/demo.php (Generic Syntax Highlighter, GeSHi) - Another powerful one loaded with as many customization options possible to the end user, a good thing, its downloadable too.
3. http://puzzleware.net/CodeHtmler/default.aspx - A very good, simple interface (yes, white rules) and downloadable.
4. http://www.chami.com/colorizer - A simple, yet effective one for good user experience while viewing code, downloadable.
5. Iris Syntax Highlighter: The best one I should say, supports from A - Z languages/tools from ANTLR parser generator to Zope DTML, great job, again downloadable.
6. quickhighlighter.com - A nice one with many options to customize the HTML source output, some good features are word wrap, option to add line numbers, etc.