There are loads of links to Infocom games that can be played online or to abandonware. Wikipedia is a great starting point:

http://en.wikipedia.org/wiki/Infocom

Boxed copies of many Infocom titles are expensive, so consider buying a copy for a less popular platform. That way, you get the boxed experience with the humorous manual and accessories. The data files can then be copied from the original disk onto a disk for a different hardware platform. Naturally, you'll need to check the FAQs for information about Infocom engine and data compatibility.