Here is a list of my favourite development tools. :

<strong>Version Control</strong>
<a href="http://git-scm.com/" target="_blank">Git (Distributed)</a>

<strong>Continuous Integration Management</strong>
<a href="http://www.jetbrains.com/teamcity/" target="_blank">TeamCity</a>

<strong>Development IDE</strong>
<a href="http://www.jetbrains.com/IDEA/" target="_blank">IntelliJ IDEA</a> (Java)

<strong>Configuration Management</strong>
<a href="https://puppetlabs.com/puppet/puppet-enterprise/" target="_blank">Puppet</a>

<strong>Build Tools & Package Management</strong>
a href="http://maven.apache.org/" target="_blank">Maven</a>

<strong>Profiling</strong>
<a href="https://visualvm.java.net/download.html" target="_blank">VisualVM</a>
<a href="http://www.yourkit.com/overview/index.jsp" target="_blank">YourKit</a>

<strong>Production Monitoring</strong>
(which version deployed to which environment). 
For example, Nagios, OpenNMS and HP Open View.

<strong>Logging</strong>
<a href="http://logback.qos.ch" target="_blank">Logback</a>
<a href="http://www.slf4j.org" target="_blank">SLF4j (logging abstraction)</a>

<strong>Testing Tools</strong>
<em>Low Level Tools (Code Level)</em>
<a href="http://www.junit.org/" target="_blank">JUnit</a>

<em>Mid Level Tools (Functional/Component level)</em>
<a href="http://www.soapui.org/" target="_blank">SoapUI</a> (Functional Testing: Create mock data services)

<em>High Level Tools</em>
<a href="http://www.seleniumhq.org/" target="_blank">Selenium</a>
<a href="http://fitnesse.org/" target="_blank">Fitnesse</a>
<a href="http://www.rallydev.com/test-management" target="_blank">Rally</a> (Agile)

<strong>Code Tools</strong>
<a href="http://findbugs.sourceforge.net" target="_blank">FindBugs</a> (Code Analysis)

<strong>Document Databases</strong>
<a href="http://www.mongodb.org/" target="_blank">MongoDB</a>

<strong>Graph Databases</strong>
<a href="http://neo4j.org/" target="_blank">Neo4j</a>
<a href="http://keylines.com" target="_blank">Keylines (Web graph visualisation)</a>


<strong>Mobile Development</strong>
<a href="http://www.sencha.com/" target="_blank">Sencha Touch</a>

<strong>Graphics</strong>
<a href="http://www.getpaint.net/" target="_blank">Paint.NET</a> (Bitmap Editor)
<a href="http://www.inkscape.org/en/" target="_blank">Inkscape</a> (Vectors Editor)
<a href="http://www.colorschemer.com/" target="_blank">Color Schemer</a>
Pixel Ruler

<strong>REST and OData frameworks</strong>
<a href="http://restlet.org" target="_blank">Restlet</a>
<a href="https://jersey.java.net" target="_blank">Jersey</a>
<a href="https://code.google.com/p/odata4j/" target="_blank">OData4j</a>

<strong>Useful Tools</strong>
<a href="http://notepad-plus-plus.org/" target="_blank">Notepad++</a> with XML and JSON extensions
<a href="http://www.scootersoftware.com/index.php" target="_blank">Beyond Compare</a> (Code & Config Comparison)
<a href="http://www.xmlvalidation.com/" target="_blank">XML Validation Tool</a>
<a href="http://getglimpse.com/" target="_blank">Glimpse</a> (Diagnostics platform for web apps)
<a href="http://www.trilead.com/Download/" target="_blank">VMX</a> (Virtual Server Management)
<a href="http://wixtoolset.org/" target="_blank">WIX</a> (Windows installation package builder)
<a href="http://fiddler2.com/" target="_blank">Fiddler</a> (HTTP debugging proxy)

<strong>UI Software</strong>
<a href="http://balsamiq.com/" target="_blank">Balsamiq</a> (Wireframing Software)
<a href="http://www.crazyegg.com/#." target="_blank">Crazy Egg</a> (Eye Tracking Software)

<strong>Charting libraries</strong>
D3
gRaphaël
Highcharts
AngularJS
Telerik Kendo UI
aCharts
Cubism.js
Dojo GFX
dygraphs
Flot
Flotr
Flotr2
Google Chart Tools
Envision.js
Javascript InfoVis Toolkit
jqPlot
jQuery Sparklines
jQuery Visualize
milkchart
RGraph
Rickshaw
Timeplot
GraphUp