Written by Giles Bennett
There's a handful of modules that I keep coming back to time and time again. Some are free, some are paid, but they're all so good - they do what they say they'll do, without fuss and hassle - that I'll install them on pretty much every site I'm involved in. And here (in no particular order) they are :
Ajax Add To Cart by J2T
In an environment where Ajax Add To Cart modules are ten-a-penny, this one stands out, for me, for a number of reasons. First and foremost is the support - Jon is exceedingly responsive and exceedingly helpful via email and has (on a couple of occasions) gone the extra mile for me in resolving any issues on integration with heavily customised themes - I stress, that for most themes, it just works, straight out of the box.
The second would have to be the number of features, and the configurability - the admin panel has a great range of options. Finally, the price - at €24 or so, it's an absolute snap.
Wordpress integration by Fishpig
This...I just love. Very few modules do so much, so well, so seamlessly, and for free, but this one is up there with the best of them. Setup is a snip, and the output integrates so well into your site that you'll wonder where Magento stops and Wordpress starts. The ability to benefit from the best of both worlds, with access to Wordpress' widgets and extensions, but in-built into your Magento store, with the ability to relate products to posts, products to categories, and more, means that clients who are used to blogging through Wordpress won't have to give that up, or compromise with a lesser Magento module, when they switch to Magento.
Sagepay Suite by Ebizmarts
If Sagepay (certainly for UK retailers) is the no-brainer choice, then the installation of this module is a no-brainer choice which follows hard on its heels. Supporting all methods of integration (both for the front-end and also, crucially, when creating orders in the admin panel provided you have a MOTO enabled account) that Sagepay offer, plus excellent reporting and Third Man fraud checking integration, it's reliable, fully-featured and another of those modules that does everything you need it to.
There is a paid for module available - the main benefit of this is that it comes with a better level of support (I can testify) is excellent as the guys will go above and beyond to sort out any problems by email and by accessing your site. In terms of features, for me the jury is still out on whether the (quite hefty, to be sure) price tag is justifiable, but certainly for larger commercial clients it's well worth the additional expense.
AOE Scheduler by Fabricio Branca
Maybe not one for the average user, but this module gives a single point of access to all the cron jobs which are running under Magento - it lets you see what cron jobs are enabled, when they run, as well as being able to enable and disable cron jobs directly from the admin panel (rather than having to edit the config file for the relevant module) and view past and future cron schedules. A great little module.
Royal Mail by Meanbee
If you're looking to get Royal Mail shipping rates, then this module is the one for you - simply tell it what methods you want to offer (domestic and international methods are supported), what markup (fixed or percentage) you wish to apply, and it'll return the appropriate options duly priced up. Although it doesn't use live rates, Royal Mail give a great deal of notice of any price changes - generally in April in each year - and with frequent updates from the Meanbee team, you're unlikely to be caught out.
Seamless Delete Order by EM Themes
A lot of people are surprised that Magento doesn't come with the ability to delete orders (although perhaps it does now that 1.8 has been released - I haven't checked yet!). From an accounting perspective, however, it's logical that it doesn't - from an accounting perspective, all orders have to be maintained on the system, whether they're completed, cancelled or closed. But sometimes you just want to get rid of test orders, and this little module, which adds an entry to the mass action list of the Manage Orders screen, allows you to do just that.
Maintenance Page by ArtsOn.IT
Invaluable if you ever need to work on a live site - this module allows you to create a simple 'under maintenance' page which visitors are diverted to (when the module is active) but which logged-in admin users don't see - so you can continue to browse and work on the store as usual. If you absolutely have to make edits to a live store, then don't consider doing it without this module in place!
There may well be a few more that make it into a second post on this subject, but in the meantime have I missed out a module that you can't live without? Feel free to share your essential Magento modules in the comments below!