KeyHelp

Free ActiveX control to enhance the capabilities of compiled Microsoft HTML Help systems, e.g. for using popups, embedded windows, auto-sizing windows or information types.

Price: free (Freeware)

http://www.keyworks.net/keyhelp.htm

LinKit!

Allows you to link any context sensitive help or HTML file to Windows applications without the need to modify the source code. The followed approach cannot be recommended as an alternative to creating conventional help, but it is an interesting option if you have to provide domain-specific information for third party software. For example, a company could decide to use some off-the-shelf project management software and add some context sensitive instructions for employees on company-specific policies.

Price: depending on number of installations; starting at approx. €3,000

http://www.affixion.com/en/

SHO Guide

Delivers step-by-step guidance directly inside the user interface of an application (requires the use of a special player software).

Price: approx. $17000

https://www.transcensus.com

HelpBubble .NET

Implements a .NET balloon style popup help window replacement for standard .NET tooltips. It allows you to easily add balloon style popup windows to your applications with multiple lines of text, buttons, titles and hyperlinks using standard HTML tags formatting, including forms. Links can open a web site, jump into online help or launch an external application.

Price: approx. $127

http://www.componentdesigns.com

Zoom Search Engine

Adds sophisticated full text search to browser based online help files and web sites.

Price: approx. $99 (professional edition); free version for up to 50 indexed topics available

http://www.wrensoft.com

H2Reg

Small utility to register MS Help 2.x Collections (Namespaces, Titles, Plug-ins, Filters) without using MSI (Microsoft Installer).

Price: approx. $100

http://helpware.net

xchm

Can be used to display CHM files on Unix systems. Cross-platform GUI front-end to chmlib (http://www.jedrea.com/chmlib/). Can display content tree, index, full text search and bookmarks.

Price: free (Open Source)

http://xchm.sourceforge.net

kchmviewer

CHM viewer for Unix, Mac and Windows. Does not require KDE, but can be compiled with full KDE support. May also be used to display help files written in Russian, Korean, Chinese and Arabic.

Price: free (Open Source)

http://www.kchmviewer.net

If you want to see how a specific page looks in different browsers you can use a service like http://browsershots.org. If you prefer to download individual browsers for more detailed testing, here are some links to the most widespread ones:

Internet Explorer

http://www.microsoft.com/windows/products/winfamily/ie/default.mspx

Firefox

http://www.mozilla.org

Opera

http://www.opera.com/products/desktop/

Safari

http://www.apple.com/safari/

Chrome

http://www.google.com/chrome

Maxthon

http://www.maxthon.com

Epiphany

http://www.gnome.org/projects/epiphany/

Konqueror

http://konqueror.kde.org

The following tools can be used to check hyperlinks:

DRKSpider

Checks internal and external links, style sheets, images and other files of a web site or browser based help system.

Price: free (Open Source)

http://www.drk.com.ar

Xenu's Link Sleuth

Checks web sites for broken hyperlinks. Link verification is performed on links which appear in <a> tags, as well as images, frames, plug-ins, backgrounds, local image maps, style sheets, scripts and Java applets.

Price: free (Freeware)

http://home.snafu.de/tilman/xenulink.html