These free dictionaries, Pali – English & Sanskrit- English, are written by my kind friend Tong Phuoc Khai. They are cool. You even do not need any Pali or Sanskrit typing software to look up a Pali/Sanskrit word with these applications.

Direct links:
Pali Dictionary
http://cuongdang.info/buddhism/Pali_Dict_updated.zip

Sanskrit Dictionary
http://cuongdang.info/buddhism/Sanskrit_Dict_updated.zip

Another free software (open source)  for studying Pali and Theravada Buddhism is the Pali Text Reader.

Hope it helps.