A set of tools for building graphs, flowcharts and diagrams

There are many different services that make life easier for a web developer or designer, including creating different graphs, charts, flowcharts, etc. Below is a small selection.
(Caution, many images)

All images are clickable and lead to the corresponding resource.

Services

Amcharts

Amcharts is a set of flash-based diagrams for sites. It can extract data from CSV or XML files, it can also receive data generated dynamically using PHP, .NET, Java, Ruby on Rails, Perl, etc.

Anychart

Flash based visualization solution. There are not only the web, but also desktop applications.

Autodesk

It offers tools for drawing circuits of electronic boards, diagrams, various kinds of UI. It does not require any additional plugins - only a browser that works with JavaScript is required, it is cross-browser. Supports export to PDF, JPG, PNG, and SVG.

Barchart

Used to build bar graphs, in other words, histograms.

Best4c

Best for Charts. It is used to build various kinds of diagrams and schemes.

Bubbl

Creates multi-colored schemes.

Chartartemo

Online tool for creating various charts, supports labels and legend.

Chartgizmo

Allows you to create various graphics for sites, blogs, profiles, etc. It may be useful for visualizing scientific, financial or any other information.

Createagraph

An online service that supports 5 different graphs and charts of your choice.

DrawAnywhere

Flowcharts, various organizational, hierarchical graphs. Supports export to PDF.

Emprise

Supports various types of graphs, axis scaling, auto zoom, etc. It features high interactivity.

Flowingdata

It works directly from the browser, it is recommended for visualization of various statistics.

Flowchart

Supports drawing a variety of objects (from lines and triangles to Bezier curves), exports to PDF or PNG.

Fooplot

A simple service that supports the construction of graphs and charts.

Gliffy

Excellent service for creating various diagrams, a very nice looking interface and many features.

Mindomo

Allows you to create and edit connection diagrams.

Mindmeister

A very flexible tool for creating various connection diagrams.

MGraph

A simple tool for creating diagrams.

Pareto-chart

Online chart generator, supports seven starter tools for free.

Rich chart live

Free service, supports various charts, graphs, etc. Powered by Flash.

WebSequenceDiagrams

Service for creating schemes. A key feature is the description of circuits in a kind of programming language.

Simpleseating

Excellent service for the analysis of various information.

Smartchart

The service for various kinds of planning, also supports diagrams, is free.

Statistics toolbox

Powerful tool for statistical modeling and analysis. Positioned to study statistics in practice.

Track-n-graph

A simple, but nice-looking service for building charts.

Libraries, plugins, developer tools

Plotr

Lightweight framework for drawing simple graphs and charts. It does not use Flash, and does not support interactive elements.

Plotkit

JavaScript charting library, supports HTML Canvas.

jqPlot

Open Source plugin for jQuery library. Supports all kinds of lines and types of graphs.

Google charts

A diverse set of tools for creating charts and graphs, including a JavaScript library.

Highcharts

JavaScript library for creating interactive graphs and charts.

Dygraphs

Another JavaScript library, Open Source.

Protovis

Uses JavaScript and SVG for native rendering.

jQuery Sparklines

Plugin for jQuery, generating inline-schemes and graphs.

jpGraph

A powerful library that uses PHP to display.

Flot

jQuery charting plugin. Forms graphs on the fly on data sets.

JavaScript Diagram Builder

A simple library for JavaScript, allows you to draw graphics on web pages.

gRaphael

JavaScript library for embedding graphs and charts on a web page.

pChart

Completely free php framework.

Fusioncharts

Available for multiple platforms. Integration with ASP, ASP.NET, PHP, JSP, ColdFusion, Ruby on Rails, etc. is possible. There are flash and HTML5 products.

Who cares, most of the collection is taken from here .

If someone believes that something is missing in the post - write, add.