From Massimo Fabiano:
Acrylic is a local DNS proxy which improves the performance of your computer by caching the responses coming from your DNS servers. With Acrylic you can gracefully overcome short downtimes of your DNS servers without disrupting your work, because you will at least be able to connect to your favourite websites and to your e-mail server. In addition Acrylic can help you to effectively block unwanted ads through the use of HOSTS files. Version 0.9.3 may include improved caching algorithms with negative responses and silent updates. Improved user control over caching with two new related configuration params. Optimized loading of very large HOSTS files on application's startup.