Playing over at the Guild we use the Portable Compendium for basically everything. It is free, currently supported, usable offline and has everything in the edition in an easy searchable format that you can also save bookmarks in. Not sure what the policy is for linking it on here, but if anyone wants a link to the portable compendium, toss me a PM. You could also come play with us over at The Guild Living Campaign if you are interested in playing 4E...