Most platforms and mobile devices have apps which understand the "stardict" dictionary format. As a result, you can easily add new stardict dictionaries, and search them. Here, you will find stardict files for sanskrit dictionaries (monier-williams, apte), and grammar texts.The input format is a simple subset of the itrans scheme. It is designed for ease of input on mobile devices, and should be relatively natural.
Note: this input scheme is a variation of the itrans format. It purposely omits all punctuation, which makes it easy to type on mobile devices. Since stardict applications generally accept case-insensitive input, searching becomes simple, while remaining almost lossless.
computers / laptops:
Note: the apte files were generated from the "sandic" project files. That project is available from http://sourceforge.net/projects/sandic/
Here are some additional stardict files related to sanskrit grammer
Here are some files related to the aṣṭādhyāyī (indexed by sūtra number and sūtra text, following the hrasva mahābhāṣhya numbering)