Macintosh provides unicode fonts and keyboards for many Indian Languages since the introduction of Tiger. The language support is built into the operating system itself. The indian languages Tamil, Sanskrit, Hindi, Marati, Bengali etc. are supported. Textedit, Keynote, Pages, Mail, Filemaker pro and many other software support these unicode fonts. It is possible now to send email in tamil or hindi or sanskrit using the email clients Mail and Entourage. Thunderbid also supports this scheme.
The operating system comes with a Tamil unicode font Inaimathi and supports two keyboard options, namely Anjal (almost phonetic) and Tamil99.
To activate the support for Tamil Language,follow the following procedures.
Step 1. Open System Preferences
Step2. Click the International Option in personal section
Step 3 Click on edit List under Languages Menu
Step 4: Tick the desired language and click ok to go back to International menu
Step 5
Click on Input Menu and choose the Anjal and Tamil99 input Method
Step 6. Close sytem Preference menu.
To use the Tamil keyboard and font in textedit first open the text edit application and then click on the american flag icon 
on the upper right corner in the menu bar and choose Anjal from the drop down Menu. (optionally the keyboard also can be chosen to get a virtual keyboard.
The American flag will turn into 
Now start typing the following key sequence
agara muthala ezuthellAm aathi pagavan muthtrRE ulagu
this will appear on the textedit
அகர முதல எழுத்தெல்லாம் ஆதி பகவன் முதற்றே உலகு (the font is Inaimathi a unicode font).
To switch back to english click at the same anjal symbol (on top right corner) and select US. Thus by clicking on the US symbol one can type in various languages in the same document
Devanagari-qwerty can be chosen in the same manner to type in sanskrit. The Devanagari keyboard layout is as under (pdf here):
#1 by yash on February 6th, 2009
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dont forget f for half letters.
#2 by Uma on May 24th, 2010
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This is great, thanks! Any tips on using these fonts in Mac Office (Word, mainly)?
#3 by Dr.M.Sundararajan on July 29th, 2010
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Dear Sir,
I am new to Mac OS. I am using iMac with Snowleopard OS and Firefox 3.6 browser. I am not getting Tamil letters displayed in my browser. Only small boxes appear. In the language edit list there is no Tamil option. Kindly help. Thank you.
#4 by ராம் on September 22nd, 2010
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Thanks for the valuable info. I love mac even more now..
#5 by ராமனாதன் on October 30th, 2010
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நன்றி. முழுமையாகப் பயண்படுத்திப்பார்த்து விட்டு மீண்டும் வருகிறேன். Keyboard layout?
#6 by ஶ்ரீனி on December 21st, 2010
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மிக்க நன்றி. தமிழ் தட்டச்சிற்கு கூகிள் ட்ரான்ஸ்லிடரேஷனை உபயோகித்து நொந்து நூலாகியிருந்தேன்….
-ஶ்ரீனி
#7 by விஜய் on February 26th, 2011
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நான் மேக் கம்ப்யூட்டருக்கு புதியவன். இது மிகவும் பயனுள்ளதாக இருந்தது. நன்றிகள்!!
#8 by sugumarje on March 28th, 2011
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அருமையான தகவல்… இப்பொழுது நான் மேக் கணிணிக்கு மாறி இருப்பதால் இந்த செய்திக்கு என் பாராட்டு
#9 by பாபு on April 17th, 2011
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இட்து மிகவும் எளிமை. நன்றி.
#10 by Lavey Prabu J on July 18th, 2011
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What is the automatic Unicode Tamil font in Mac ? Because when we see the tamil unicode websites in windows, it automatically choose the “Latha” font to show the pages. What about the Mac ? Please clarify. Thank you !
#11 by Vasanth Kumar S on August 6th, 2011
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என் Mac புனர் ஜென்மம் பெற்றது..
#12 by vasu on October 22nd, 2011
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Prabu J – I think the font used by Mac OS X is Inaimathi