This component certainly stands out for its ease of use and wealth of features.
However, the fact that the output is based on a restrictive table based layout, makes styling it a complete nightmare.

It addresses a major flaw in the way Joomla 1.5 core handles meta titles. Extremely handy and worth installing on any site.

We are using JUGA on several complex portals, including an Intranet. Among other neat features, this extension empoers us to define which task of a give component can be performe by whom. Granularization of privileges at its best, in deed.
Furthermore, restrictions can be applied on content items, components, modules and menu items.
As the subject line suggests, it does not patch a single file. Instead, restriction policies are enforced through a plugin.
Finally, it supports seamless integration with AEC subcription plans.

Have used CB JUICE in a couple of major projects with hundreds to over 2000 thousand users each. The whole process is straightforward and bug free.
Just had to convert XLS spreadsheets into CSV files, name and set the headers order properly, upload the CSV file and that was all. Immediately my CB and core Joomla user tables had the pertinent data stored.
I can even update the user data in edit mode every time the CSV file is changed (existing entries can be kept and new ones are added).
The latest version doesn't seem to support MySQL 4, but that's not really a show stopper these days. Highly recommended for time saving developers.

If there's something i appreciate about any piece of software is the ability to reuse and refocus it for several different purposes.
With customizable fields, AdsManager has allowed me to turn a "classifieds" script into a neat Job Board. Together with the PCS extension, one is even able to charge fees for ads. Stunning.
Last but not least, ethics. Contrary to a growing tendency among certain 3rd party developers, Thomas puts the GPL compliance banner above immediate profiting. An attitude which is worth praise and gratitude (in the form of a much deserved donation).

PollXT outperforms the default Joomla polls toy by far and seems to have no serious competitor in this area.
However, it might need some serious recoding, as it keeps on freezing Firefox 2.0.0.3 after a while. I can hardly finish even the simplest task without a hang.
It is in deed feature rich, but at this stage it requires loads of patience to work with.

VFM is a very promising component, in that it provides eyecandy and a granular ACL which empowers site admins to set access levels on files per user or group, without patching any core file.

I'd just like a little detail to be modified. In the current version, most admin tasks take place in the frontend. I think it would be a lot better to handle these tasks in the backend, for the sake of convenience and consistency.