Specification :

"99 Names of Allah" (in Arabic: "Asma-ul Husnaa" = The Excellent Names) are the epithets of Allah`s attributes mentioned through the The Holy Koran and Hadiths (sayings of The Last Prophet Muhammad {peace of Allah be upon him}). Indeed, the names and attributes referring to Allah in the Koran and sayings of Prophet Muhammad (pbuh) is more than a hundred. The phrase "Asma-ul Husnaa" contains the whole of this names and attributes in general meaning. However it is a special term for the 99 Names of Allah in Islamic literature.
"Asma-ul Husnaa" have a very special significance in Islamic belief. Because firstly in the Koran, Allah says: "Allah`s are the excellent names, therefore invoke him by them. (7:180)". Secondly, as the teacher and explainer of the Koran, Prophet Muhammad (pbuh) said: "There are 99 names of Allah; he who commits them to memory (in the narration of Ibn `Umar this part of sentence is: "he who enumerates them") would get into Paradise. Allah is Odd (i.e. he is One and 99 is an odd number) and He loves odd number: ...(Than the reporter Abu Huraira enumerates the 99 Names)..."
Because of this significance, hundreds of "Asma-ul Husna explanation books" have been written [and is being written, even on the web ;-)] by Muslims. Many leading Muslim writers and scholars in the Islamic history had wanted to add their book series also an "Asma-ul Husna explanation" book. There is even books that only examining the books written about "Asma-ul Husna".
There is absolutely an "Asma-ul Husna" collection in the works of a Muslim calligrapher. Many Muslim teachers and parents ask their students and children to memorize "Asma-ul Husna" by promising them some gifts. Many good Muslims enumerate "Asma-ul Husna" every day especially after the day`s first praying expecting the spiritual advancement and to get into Paradise as Prophet Muhammad (pbuh) heralded.
One may ask: "How come only enumerating or memorizing these names can result the spiritual advancement and getting into Paradise ?"
" The Holy Prophet Muhammad (pbuh) again and again instructed and advised his companions to keep their hearts always illuminated with the remembrance of Allah. "
In the Koran Allah says: "...and certainly the remembrance of Allah is the greatest, and Allah knows what you do." (29:45), "Those who believe, and whose hearts find satisfaction in the remembrance of Allah: for without doubt in the remembrance of Allah do hearts find satisfaction." (13:28) Prophet Muhammad (pbuh) said: "... Beware! There is a piece of flesh in the body if it becomes good (reformed) the whole body becomes good but if it gets spoilt the whole body gets spoilt and that is the heart."(Sahih Bukhari / Belief (Al-Eman), Volume 1, Book 2, Number 49)
"According to him, the heart is the source of good and bad thoughts and deeds. If there is a slackness on the part of a believer in the remembrance of Allah, bad ideas and thoughts occur in it. At the end they result in sins or vices. When the remembrance of Allah is in abundance, bad thoughts and ideas are suppressed and good ones occur which lead to good deeds. "
If we keep in view the verse of Koran mentioned above (29:45) we can realize the relationship between remembrance of Allah and the deeds it resulted: After mentioning about remembering Him, Allah says: "and Allah knows WHAT YOU DO."
So, memorizing or enumerating the Excellent Names of Allah, will result in remembering him; remembering him will result in the illumination and goodness of the heart; this good heart will result in the good deeds; and the good deeds will take the person into Paradise by the permission of the Lord Of the worlds Allah.