Sun's free VirtualBox software has made it extremely easy to run Linux concurrently with OS X, and there are various HowTo's on the web (e.g. this one) for doing it. Some reasons this could be useful are a) to use the variety of Windows fonts available for Indic and SE Asian scripts where the Mac only has a couple or none, and b) to use input methods for these scripts which are not yet available for OS X.
I installed Ubuntu this way and everything worked well. It comes with the IBus framework that includes a large number of IM's -- For example there are 6 for Devanagari (Inscript, Phonetic, Remington, iTrans, Typewriter, Harvard-Kyoto). You can also install the SCIM platform if you want. Copy/paste from the included OpenOffice suite to OS X apps was no problem.
A couple drawbacks: I could not find anything like Keyboard Viewer (or Help files) to assist in figuring out how various IM's or layouts work, so you need to get that off the internet or someplace else. Also Ubuntu only lets you have 4 ordinary keyboard layouts active at once (the number of IM's seems unlimited).
I tried out Linux once before 10 years ago...