Turbo Lister is an offline eBay ad creator with a full set of listing options and built-in HTML editor. Listings are saved for future use.
The interface is quite cluttered, but a definite improvement over the Sell Your Item pages. The amount of space given to different aspects of the listing could be apportioned better though: listing upgrades - which are often tinkered with - get barely more space than payment methods, which most sellers rarely change.
Listing fees can only be calculated by moving listings to the 'Upload' tab - it would be more useful if the fee was shown in real-time as the start price and upgrades are changed.
The main advantage of Turbo Lister is offline ad creation and saving listings for easy reuse. If that's what you need it's a good free solution.