Replacementdocs
Nice Website on which you can find Manuals to old games. In case you “lost” yours. This comes in handy when you play one of those old games that suddenly ask you for word X on page X. Link

Dosbox
There isnt really much to say.
The probably best Emulator for Dos Games in the Net.
Link

ScummVM
Another Great Emulator.
It doesn’t support as many games as Dosbox but still is very good.
A nice difference is that you just add the game(without any mounting as in dosbox)and then you are ready to play. Another cool thing is that it bypasses the copy protection of some games (for example Indiana Jones and Monkey Island)
Also it even supports some newer Games like Broken Sword 1-2.
Link