Does your site send out HTML-based emails? If so, then you should be aware of the Email Standards Project web site. This site provides a plethora of information on how to ensure your HTML-based emails are rendered properly on a maximum number of email clients.
The site provides a super-simple email client scorecard on the homepage (surprise - Outlook is rated "poor") as well as an acid test for email clients.
One of the first things I do when creating a new site is to set the Administrative Theme (admin/settings/admin) to Garland. Two of my main reasons for doing this are:
If you build Views with lots of display attachments, you've no doubt run across the hurdle of re-ordering the attachments. There's no drag-and-drop method of doing so - often developers are forced to go into each attachment changing the attachment position several times in order to wrangle the attachments to the desired order.
One way of getting around this is to export the view, bring the export text into a text editor, and manually move the attachments to the desired order simply by cutting and pasting the attachment code and then re-importing the view.
The Views module has a little-talked about default view that provides a way to display all internal content that links to a particular page. Think of it as an internal "trackback" (or "pingback") that you often see on blog sites.
For example, when exposed as a block, the "backlinks" view displays a list of all the other content on your site that links to the current node. The page view can also be used - the view accepts a node ID as an argument to filter which backlinks are displayed.
When creating a sub-theme, if you want to add a new region to it, you must remember to redefine the default regions - or bad things will happen.
Here's an example: let's say you're creating a new theme called "squirrel" based on the 960 theme. Since the 960 theme uses Drupal's default regions if you just add your new region to the squirrel.info file, you'd find that all of your inherited (default) regions are now gone and your admin/build/block page is full of messages saying that all your blocks have been disabled.
When theming a Drupal site, I find that there are no sweeter words to hear from the client than "IE6 support is not necessary". Unfortunately, this phrase is far from commonplace. Currently, IE6 has about a 17% market share, so while it is shrinking, it is probably not small enough yet to ignore (but what a glorious day that will be).
I was recently was asked by a client to assist them in creating and displaying a block that would only appear on certain pages within the site. In their case, they wanted to only display the block on node pages - but only when the node was of a particular content type.
The Portable Network Graphics (PNG) format is a great way to display graphics on the web. It is meant to be a one-for-one replacement for the Graphics Interchange Format (GIF) but without all the proprietary craziness (for awhile there, UNISYS owned a patent that involved the GIF format). Unfortunately, its adoption has not been as fast or as complete as one would have hoped. The PNG format is lossless and generally compresses images better than GIF.
Whenever it's time for you to upgrade modules on your site, you should have a checklist of the steps involved. One step I've recently added to my checklist is to clear the site cache just prior to uploading the updated module files.
Drupal's core "Path" module is a great way to rename a URL on your Drupal site to something more user-friendly. Instead of telling a potential client that your "services" page is at www.example.com/node/324, you can just tell them to go to example.com/services.
The "Content Copy" module is a great little module that ships with CCK and provides a handy capability that not everyone is familiar with.
Most developers build a site on the local machine and then upload everything to the live server when they're ready. What happens when they want to add a new content type to the live server though?
With over 4,000 available modules, there's no way that anyone can know what each and every single module does. In my opinion, many developers often resort to writing custom modules too quickly without doing their due diligence in looking for an existing module to accomplish the same task.
When I'm working on a site that I think might require a custom module, there's a few steps I take before I break open my code editor (currently Espresso).
Need to write a module that implements a form that needs some AHAH magic? Then use the awesome AHAH Helper module.
Drupal's Batch API is a great tool for module developers to leverage when an extended task needs to be performed. The Batch API is used during Drupal's own core installation and by modules like Node Import.
Unfortunately, sometimes the default settings of PHP's mod_security extension can interfere with some implementations of Batch API.
I've imported my fair share of content using the Node Import module and one thing I always watch out for is empty data. Spreadsheet with blank columns that need to be imported always seem to cause problems.