Here you can find tools to use in your projects. (This is a very selective list).

App Builders

Mozilla App Maker

App Maker Wiki + How-to

Social Media

Twitmaps : create a map from a twitter stream. 

Data Visualisation

Google Fusion : create tables from spreadsheet data. (For arduino: cut and paste from serial port output into google spreadsheet and choose a chart type.)

Leafletjs : create maps -- needs a knowledge of javascript

Google Map Maker : create maps using google maps (there are many map generators available on-line for google maps…)

Micro-controllers and Sensors

Arduino : lots of help , examples and discussions

Instructables : tons of step-by-step examples