Dua before Eating:
بِسْمِ الله وَعَلَى بَرَكَةِ الله

In the name of Allah and upon the blessings of Allah. (Al-Hisnul Haseen)

Dua if one forgets Dua Before Eating:
بِسْمِ الله اَوَّلَهُ وَاخِرَهُ

In the name of Allah in the beginning and the end. (Abu Dawood)

Dua in Anticipation of Ramadan:
On the authority of Anas (may Allah be pleased with him): The Messenger of Allah (may Allah bless him and grant him peace), used to say the following when the month of Rajab began.
اَللّهُمَّ بَارِكْ لَنَا فِى رَجَبَ وَ شَعْبَانَ وَ بَلِّغْنَا رَمَضَان
“Oh Allah! Bless us in Rajab and Sha`ban, and bring us, oh Allah, to Ramadan.” [Narrated by Tabarani and Ahmad]

Dua for Suhur:
When beginning the fast – Suhur (sehri)

وَبِصَوْمِ غَدٍ نَّوَيْتَ مِنْ شَهْرِ رَمَضَانَ

I intend to keep the fast for tomorrow in the month of Ramadan. [Abu Dawud]

Transliteration: Wa bi-sawmi ghadin nawaytu min shahri ramadan

Dua for Iftar:
When breaking the fast – Iftar
اللَّهُمَّ اِنِّى لَكَ صُمْتُ وَبِكَ امنْتُ [وَعَلَيْكَ تَوَكَّلْتُ] وَعَلَى رِزْقِكَ اَفْطَرْتُ
O Allah! I fasted for You and I believe in You [and I put my trust in You] and I break my fast with Your sustenance.
["wa ‘alayka tawakkaltu" is quoted in some books of knowledge - but not all, hence it is in brackets]. [Abu Dawud]

Transliteration: Allahumma Inni laka sumtu wa bika amantu [wa alayka tawakkalto] wa ‘ala rizqika aftartu

Source: www.haqislam.org