Many times when coding a custom module, there is a need to store a number of variables. I've seen many developers use the variables table using variable_get(), variable_set(), and variable_del(). The problem with doing that is all of those variable get loaded on

An example module which integrates the Flag module with a custom form.

Most configuration can be exported with Features; path aliases seem to be an exception. So, to export a path alias, I use the following technique in mymodule.install:

"The Pathauto module automatically generates URL/path aliases for various kinds of content (nodes, taxonomy terms, users) without requiring the user to manually specify the path alias. This allows you to have URL aliases like /category/my-node-title instead of /node/123. The aliases are based upon a "pattern" system that uses tokens which the administrator can change."

Gives replacement tokens. This module is used by so many other modules, you are sure to use it and learn it if you haven't already.

"This module provides an auto-increment (serial) field."

"Define dependencies between fields based on their states and values. "

Use PHP to create computed fields. If you use this, export the configuration so you don't have PHP in the db!

"auto_nodetitle" is a small and efficient module that allows hiding of the content title field in the form. To prevent empty content title fields one can configure it to generate the title by a given pattern.

When the token module is installed it's possible to use various node data for the
auto generated title - e.g. use the text of a CCK field (since 5.x).

Advanced

Inline editing for fields. Still an alpha module at the time of this writing but I've used it and it works :) One handy thing you can do is create a view that has editable fields to get custom streamlined editing interfaces.