aMember is a flexible user management script. It has support for PayPal, Clickbank, Multicards, 2Checkout, Revecom, PayPal multi-currency processing, Authorize.net, Q-Chex, E-Gold and offline payments (offline cheques/Western Union/Money Order), and allows you to setup paid membership areas on your site. It also can be used without any payment system (you can manage users manually). Unique features are support for multiple payment systems at the same time and support for multiple products (subscriptions) with different levels of access, pricing, and time periods.
WordPress FAQ is a cool plugin for creating your FAQ section . It has a lot of parameters to set, and it will allow you set your own theme from scratch. It has a user-friendly front-end and back-end interface, allowing you to set all parameters quickly and easily. FAQs have SEO-friendly URLs.
Joomla contact form builder extension is a complicated tool for making submission forms for your Joomla website. It permits you to specify parameters like colors and fonts. It can use a Google map when given an address or geographical coordinates (longitude and latitude), and the user can drag the marker to the required location.