Thought I would start a list of some of the most useful prestashop modules that I have found.
1. Product Export. This produces a CSV file of your entire product database. You can even select which columns you want to include in the file (price, name, description etc).
http://www.prestashop.com/forums/viewthread/37900/modules___development/module_product_export_module_v0_dot_1_free2. Send-to-friend now with Captcha. This is an altered send-to-a-friend module that now includes a captcha security image.
http://www.presto-changeo.com/prestashop-free-modules/29-send-to-a-friend.html3. Googlebase Shopping Script. This module creates an xml file that you can upload direct to googlebase, and will display on google shopping.
http://www.ecartservice.net/03082008/exporting-products-to-googlebase/4. Frontpage categories module. This module displays your categories in your homepage center column. It can be a bit tricky to get it to look right. Example
http://www.snowboarding-goggles.co.uk/ This module uses the images that you define for your categories when you create them.
http://www.prestashop.com/forums/viewthread/2079/modules/frontpage_categories_module5. YouTube Module. With this module you can insert a YouTube Video into your homepage center column.
http://www.prestashop.com/forums/viewthread/10352/P0/modules/module_youtube6. Homefeatured products. This is an alteration to the homefeatured products that gives you the option to randomise the products and also displays an enlarged tooltip image on mouseover.
http://www.prestashop.com/forums/viewthread/10110/P0/modules/homefeatured_module_modified_homefeatured___homefeatured27. FAQ Module. This module let you create a FAQ page from your admin area. Example
http://www.purplegiraffe.co.uk/modules/faq/faqs.phphttp://www.prestashop.com/forums/viewthread/33081/P0/modules___development/free_faq_module_v1_dot_08. Ask a question module. This module adds a link on your product page that lets your visitor ask a question about the product.
http://www.prestashop.com/forums/viewthread/10915/P75/#1950299. Share on social networks. This module adds a number of social networking icons onto your product page.
http://www.prestashop.com/forums/viewthread/31160/modules___development/module_share_on_social_network__partage_sur_les_reseaux_sociaux__eng10. Wiznav navigation bar. This module creates a customisable horizontal navigation bar into your site.
http://www.prestashop.com/forums/viewthread/17546/modules___code_contributions/module_wiznav_2_dot_1_dot_3__cat_addon11. Dropdown language and currency module. Dont like the language and currency at the top of the page? This module creates a column box, with dropdown boxes.
http://www.prestashop.com/forums/viewthread/12555/modules/module_lang_and_currency_menu12. Social networking icons. This module adds the social networking icons into the side bar. There is 2 different versions of this.
http://www.prestashop.com/forums/viewthread/11802/modules/download_rss_web_2_dot_0__social_bookmarks_09020513. Super User Module. This is an invaluable module that logs you in as a customer. You can select which customer you want to login as then go to your frontend.
http://www.prestashop.com/forums/viewthread/19172/modules/module_new_super_user_14. Paypal Pro Module. Paypal webpayments pro Module
http://www.prestashop.com/forums/viewthread/38359/modules___development/module_paypal_website_payment_pro_uk__3d_secure_implemented__free_prestashop_moduleThis is obviously not a ful list of the modules available, but is some of the most useful in my opinion.
If you have any difficulty installing any of these, drop me a pm and I will see if I can help.