AceFTP

AceFTP is a program from Visicom Media. AceFTP comes in a freeware and a Pro (paid for) versions. The freeware is not a limited version. It is a fully functioning client but with some 'nicety's' stripped out.
It is a very intuitive piece of software with a very good drag and drop interface for the main body of use but in narrow menus surrounding the drag and drop area are the common tools used to manipulate the environment (navigate folders, CHMOD, new folder and delete for example).
Towards the top of the interface is a small window which is tabbed. First tab is a log of transactions, including files transferred, responses from the server and errors. Errors are coloured red and easy to spot during use which is nice.
Second tab is the queue of items waiting to be transferred where you can remove files if necessary.
Third tab is a file viewer and to be honest is a bit rubbish, but it doesn't hurt anything.

AceFTP has the ability to store ftp credentials and stores them in individual files which makes moving them between computers very easy. It also has a feature which stores ftp URLs (or an amount of URLs) which can be very handy if you are using one location regularly for a short period of time.

Another feature included in the freeware version but often missing in other clients is the ability to maintain multiple connections and transfer between them.

Extra features in the Pro version include the ability to transfer over SSL or SSH, password protection, toolbars (if they float your boat), remote file viewing in the preview tab and a few other goodies.

Overall this is a brilliant and often underestimated client. Id recommend this client be seriously considered for an experienced user wanting a good lightweight client with the right features.
Whether the Pro version is a worthy buy is for you to decide if you need the extras. Personally id say no...