Across Lite

Across Lite is a wonderful application to solve and do excellent crosswords. The program features a nice and very intuitive user interface that includes several window display preferences to suit you best.

The application allows you to solve the entire crossword from once, as well as check or reveal a current letter, a selection only, and all letters.
You can also use pencil to mark answers that you are not sure of. All the puzzles can be saved and printed, customizing the ink blackness (to save ink) and grid position. You can also select the color of the grid, clue list, and clue prompt, although the variety offered is not so wide. You can also customize the solve preferences to adapt it to your style. As regards viewing options, you can zoom in and out, and view the complete puzzle. It even includes a small notepad to take any note that you need.
As you can see, the program is very complete and includes everything you need to check or solve any crossword you may find difficult or even impossible to solve.