My client offers seminars and classes. Using VirtueMart Orders Report, the client (very non-technical) is now able to easily generate rosters for each class, among other things, for export to Excel.
Set-up was quick and painless. Demo site does a fine job of previewing the extension before purchase.
I had created several custom registration fields that needed to be included in the reports and the developer customised my instance for a very modest price. Highly recommended for enhanced reports and export beyond vanilla VM Reports.

Version 1.5.5 for Joomla! 1.5.x. Excellent combination of component, module and plugin. SimpleCaddy does exactly what is claims... easy set up of a simple shopping cart feature using PayPal as the merchant account. Great for sites selling only a few products who don't need (or want) the administrative overhead of Virtue Mart (another great Joomla! e-commerce solution, by the way). Took 10 minutes to install and 45 minutes to configure. Once properly configured each product takes only a couple of minutes to enter. Product descriptions and photos are entered in a content page and simple plugin code calls the "Add to Cart" button.
A few rough bumps to final configuration but most answers can be found in the developer's forum. Not very customizable but highly recommended for simple selling needs when PayPal is your payment solution.

Thank you to Fraser for bringing Martin Larsen's Moshide up to date -- 1.5.x native.
I needed to present a bunch of quiz questions (no need for scores or reports) in an interesting manner. Moshide was the perfect tool for the job. Easy to plug into content items. Styling is accomplished with CSS on just a couple of tags.
Thanks again for a job well done.

...take a few hours and teach yourself how to create clean CSS formatted forms. Then use ChronoForms to do the heavy lifting of making them functional. There is now a solid 1.5 version and support through their forum is outstanding. Support these folks. This component will only get better with age.

gMaps (specifically gMapsPro) is terrific. Great way to leverage the power of Google MyMaps to present a highly interactive map experience within your Joomla website. I used it to graphically display the all the South American distribution centers that my client operates. Each distributor's marker can contain text and graphics along with a link to a Contact Us form (ChronoForm). There is also cool Community Builder integration but I've not had the opportunity to use that yet. gMapsPro for 1.5 is still in RC stage running in legacy. Has a few rough edges that hopefully will be addressed in upcoming releases. Documentation could be beefed up as well.