In this post I'm not going to describe extremely great modules that you must use on each your Drupal site such as Backup&Migrate module or Views module etc. This modules you can use in some separate cases but they can improve support of your Drupal sites!
If you have old site that was done many years ago and maybe upgraded for example from previous Drupal branch, say from D6 to D7. Than you can face with Distribution name Notice.
Notice: Undefined index: distribution_name in drupal_install_profile_distribution_name()...
You can google this issue and find solution, for example
UPDATE `my_database_name`.`system` SET `status` = '1',
`info` = '' WHERE `system`.`filename` = 'profiles/demo_profile/demo_profile.profile';
SET `status` = '1'
WHERE `filename` = 'profiles/standard/standard.profile';
But it can not help in my case, when I use my own custom profile. But it does have sense to switch to Standard one to have easy Drupal core updates etc.
And I was happy when I found Profile Switcher.
I think when project start to save some time in development we start with some Drupal distribution to have already prepared set of modules. But during project life some modules are turned off and some new modules are installed. Thus we go far from initial Drupal distribution. And some times we find a decision to switch Profile name to Standard...
I have my common practice to create for the client some separate admin user with abilities that they need only without any complex and extra admin items. Not qualified user can brake Drupal site if we provide him or her Drupal Superuser account. But sometimes we need to delegate to the client admin ability to manage users. And OMG, they can delete First Drupal user, for example. In this case User One module must be installed! After that your First Drupal user will be protected.
I think each Drupal developer noticed that after some long development activity when you install and uninstall a lot of modules and themes trying to find optimal solution for your project than Drupal become crazy slow. It is due to some out of date data in "system" table. Bootstrap optimizer fix this issue.
This module helps you to create menu that will be already on the screen or some permanently visible informational block, for example contact form. I have found it useful together with my new Anchors Panels Navigation module.
During production life time of each Drupal sites some new features appear and they require new type of content. Also some old nodes should be converted in new content types with new fields. For example several years ago I'm working on Music School site where we have Teacher profile content type. Client would like to add gallery ability for some separate VIP teachers. New Profile content type was created and some separate profiles was converted to new content type. By the way module Node Convert allow to set some mapping rules during conversion process.
Code per Node
I tried this module at first when I did video background in the header on one of page of the project of my client. It was separate page with video background and we no need to use this feature on any other pages. So I put VideoBG Jquery script, settings and paths to my HTML5 video files in the JS field in node edit form. This module provide an ability to customise pages directly from admin area without theme edit. I think it is reasonable to do when this custom JS or CSS behaviour strongly connected with current node content and thus we do not loose this behaviour when we will switch from one theme to another one.
I think every Drupal Developer use placeholder in menu that make Drupal point to the front page of the site. Void Menu module allow Drupal admins to set their own tags with some replacement rules. The most easy example, we can set in menu hashes pointed to anchors on the current page. I have found this module extremely perfect together with me new module Anchors Panels Navigation.