I am often asked by my clients which Magento Extensions I can recommend for their Magento 1 or OpenMage shop. Thats why I created a (probably incomplete) list of awesome Magento or OpenMage Extensions that I regularly use in my Magento projects - next to my own Magento 1 extensions of course:
|Mage Setup||Administration Must-Have||quickly adapt your Magento Store to German Market incl. tax, localizations, etc. (formerly called: German Setup)|
|TinyMCE HTML5 Compatibility||Administration Must-Have||fixes issues with HTML5 tags in WYSIWYG editor in Magento 1 backend|
|Attach Terms And Conditions||Checkout Must-Have||attaches agreement PDF documents (e.g. AGB) to any order email|
|AW Blog||CMS||nice, simple and effective blog extension (also used on my website)|
|AOE Scheduler||Administration Must-Have||huge improvement to the original Magento scheduler that offers a lot of actions in the backend for monitoring and crontrolling your Magento cronjobs|
|AutoShipping||Checkout Must-Have||automatically add shipping costs in cart so that the customer sees a relevant total amount value in the cart already|
|Change Attribute Sets||Catalog||provides the possibility to change attribute sets after product creation (this is not possible in Magento standard)|
|uDropship||Catalog||very huge (but also complex) extension for dropshipping capabilities|
|Recolize Recommendation||Catalog||Product Recommendation Engine|
|M2E Pro||Catalog||eBay/Amazon/Rakuten interface|
|SMTP Pro Extension||Administration||send your Magento emails through any email service|
|JS/CSS Timestamp||Performance||add last-modified timestamp to your JS and CSS merged files to enabled browser-based caching|
|HoneySpam Extension||Security||adds a little bit of bot protection to most of the forms, see more information in my blog post about captchas|
|Lesti FPC Extension||Performance||simple full page cache for Magento 1 / OpenMage|
Another list of recommended Magento 1 extensions can also be found in this Github repository.
If you want to quickly start creating responsive templates I suggest to take a look at my blog article about Magento Mobile Themes.
I always suggest you take a look at the source code of each of the extensions you are installing in your shop. Remember that every Magento extension may do everything!
Looking forward to your comments on these!