Aadhar is again in news these days. I did some quick search and have compiled this post to help you know more about Aadhar.
- So, what is Aadhar?
Aadhar is Multipurpose National Identity Card or Unique Identification card (UID Card). Though the project name mentions the word 'card', currently there's no plan to issue a card. They will be issuing only Aadhar number.
 - Will I get an Aadhar card?
No! You will just get unique Aadhar number.
 - What's the use of Aadhar number? Why should I apply for Aadhar number?
One of the answers I found on the official Aadhar Faq Page says:- Food & Nutrition – Public Distribution System, Food Security, Mid Day Meals, Integrated Child Development Scheme.
 - Employment – Mahatma Gandhi National Rural Employment Guarantee Scheme, Swarnajayanti Gram Swarozgar Yojana, Indira Awaaz Yojana, Prime Minister’s Employment Guarantee Program
 - Education – Sarva Shikhsha Abhiyaan, Right to Education
 - Inclusion & Social Security – Janani Suraksha Yojana, Development of Primitive Tribe Groups, Indira Gandhi National Old Age Pension Scheme
 - Healthcare – Rashtriya Swasthya Bima Yojana, Janashri Bima Yojana, Aam Aadmi Bima Yojana
 - Other miscellaneous purposes including Property Transactions, VoterID, PAN Card etc.
 
Aadhaar means foundation , therefore it is the base on which any delivery system can be built. Aadhaar can be used in any system which needs to establish the identity of a resident and/or provide secure access for the resident to services/benefits offered by the system. Aadhaar can be used in the delivery of the following programs: - What documents are accepted as Proof Of Identity(PoI) for Aadhar?
- Passport
 - PAN Card
 - Ration or PDS photo card
 - Voter ID
 - Driving Licence
 - Government Photo ID Card
 - NREGS Job Card
 - Photo ID issued by recognized Educational Institution
 - Arms Licence
 - Bank ATM card with photo
 - Photo credit card
 - Pensioner photo card
 - Freedom Fighter Photo Card
 - CGHS or ECHS Photo Card
 - Address Card having Name and photo issued by Department Of Post
 - Certificate of Identity issued by Group A Gazetted Officer
 
 - What documents are accepted as Proof Of Address(PoA) for Aadhar?
- Passport
 - Bank Statement or Passbook
 - Post Office Account Statement or Passbook
 - Ration Card
 - Voter ID
 - Driving Licence
 - Government Photo ID Card
 - Electricity Bill not older than 3 months
 - Water Bill not older than 3 months
 - Telephone land line bill not older than 3 months
 
 - Can I apply for Aadhar online?As of today(1st July 2011), you can not apply online for Aadhar.
 - How/where can I apply for Aadhar number?They have not started issuing Aadhar number in all the cities. Call up Aadhar helpline number ask for your nearest location.
 - Aadhar helpline number?Call 18001801947
 - What's the information asked when applying for Aadhar number?
Name, Date of Birth, Gender, Address, Parent/Guardian details (required for children, adults may provide), Contact details phone and email (optional)Biometric Information required: Photo, 10 finger prints, Iris - Where can I find more information about Aadhar?
 - Unique Identification Authority of India on Wikipedia
 - UIDAI official website http://uidai.gov.in/
 - Aadhar in news.
 - Aadhar must for LPG delivery, Deccan Herald June 23, 2011
 - Aadhar available at post offices, Deccan Herald June 24, 2011
 - Call up Aadhar helpline: 18001801947
 
If you know more information/resources on Aadhar, please share it in comments.