The Drupal User expire module "allows an administrator to define a date on which to expire a specific user account or to define a period at a role level where inactive accounts will be locked."

Requires the rules module, allows for setting a "timer" on a node and having rules do something when the "timer" hits zero.

Also see Node Expire Extras

"The Session Cache API is a super-simple two-function API for programmers to access small amounts of user-specific "state"..."

"Fieldgroup will, as the name implies, group fields together. All fieldable entities will have the possibility to add groups to wrap their fields together. Fieldgroup comes with default HTML wrappers like vertical tabs, horizontal tabs, accordions, fieldsets or div wrappers."

It's hard to find really good documentation on creating custom ctools style plugins, like the stylizer that comes bundled with panels. For example, if you search the web, you'll come up finding a link to http://dustinbons.com/panels-styles-plugin-drupal-7 which is not really a very good tutorial. If you view the advanced help module page on this, it comes up blank.

"CER keeps reference fields in sync. If you have two entities that refer to each other using Entity Reference (or some other kind of reference field), it saves you the trouble of double-editing your entities in order to have them point at each other. If entity Alice references entity Bob, CER will make Bob reference Alice, and keep the references up-to-date when either entity is updated or deleted."

How to set up a local server with Solr.

In Drupal, each module has something called weight. The weight, which is stored as an integer, determines when the module's code gets run. Sometimes, you want to alter something that another module does. In order to override another module, your module has to have a higher weight. There is nothing in the UI that lets you change a module's weight. You can set the weight by changing the value in the 'system' database column. To automate this,

John Albin says that you start with SMACSS and realize that something is missing. That's where BEM comes in handy.

This was taken from http://www.netwhisperer.com/2014/01/17/5-ways-css-preprocessors-improve-stylesheets/