The module for making forms and surveys. Often used for misc contact forms.
After a submission, users may be sent an e-mail "receipt" as well as sending a notification to administrators.
Results can be exported into Excel or other spreadsheet applications.
Also provides some basic statistical review and has an extensive API for expanding its features.
Does not use Drupal 7 Fields and Entities, has its own API, implementations and integrations - so it may be more lightweight solution, but sometimes it creates limitations on extendability.
Probides Colorbox - light-weight customizable lightbox plugin for jQuery - integration into Drupal.
Images, iframed or inline content etc. can be displayed in a overlay above the current page.
Most installed Drupal 7 lightbox module.
There are many modules which support Colorbox or extend its functionality.
ex. Colorbox node which provides an ability to display any page inside a colorbox modal without the header and footer.
Allows you to manage contextual conditions and reactions for different portions of your site.
Think of conditions as a set of rules that are checked during page load to see what context is active. Any reactions that are associated with active contexts are then fired.
Often used to manage blocks visibility depending on complex conditions when it's not possible to use core's blocks visibility.