Fabrik

Fabrik is THE open source Joomla application builder component. Fabrik gives you the power to create forms and tables that run inside Joomla without requiring knowledge of MySQL and PHP. Then feed your data into Google Maps, Charts or an AJAX based calendar With Fabrik you can create applications that range in complexity from simple contact forms to complex applications such as a job application site or bug tracking systems.

http://fabrikar.com/index.php

RWCards

RWCards  is an E-Card component for Joomla 

http://www.weberr.de/

JoomlaWatch

JoomlaWatch allows you to watch your website visitors and bots in real-time from the administration menu. Specially their IP addresses, countries they come from, geographical location on a map, which pages they are viewing, their browser and operating system, it creates daily and all-time stats from these information plus unique, pageload and total hits statistics. Furthermore, you can block harmful IP addresses, see blocked attempts stats, evaluate the trend charts, and create goals based on many parameters. In the frontend, it can show the top countries, user and visit information for certain periods of time.

http://www.codegravity.com/joomlawatch-demo.html

Sourcerer

Sourcerer for Joomla enables you to place PHP and any kind of HTML style code (including CSS and JavaScript) right in to your content! Not only in your articles, but also in sections, categories, modules, components, META tags, etc.

http://www.nonumber.nl/sourcerer?tab=Examples

Hi Aleistere! Thanks for the interesting suggestions. Some of what these extensions feature is actually being built directly into Wiccle 1.0, and modules for eCards and CRM are on our roadmap for near-future versions.

These all feature cool functionality, but at a quick glance, especially 1, 3 and 4 seem to be integrated with Joomla systems quite deep... I am ideally looking for plugins that are either plug & play (more like widgets), or require a simple integration layer to work. (Extensions making heavy use of Joomla/other classes are quite hard to port to another system.)