What are the reasons for having special names for God/ Jesus? I was watching the "Truth Project" (a religious DVD) and the speaker kept referring to "Jehovah Jireh".    A recent answer here makes a reference to "Yahshua Ha-Maschiach", whom we have to infer is Jesus.

Q: What are the intended purposes by those who would use "unusual" names for God or Jesus?

My speculative answer is that such persons believe they are beholden to a specially refined orthodoxy-- hey we all do to some extent-- but believe they need to refer to a more special name in order to clue others that they have many false ideas about the "god" they worship. 

If this answer is wrong, I beg forgiveness and correction.
some of the Names come from the difference in Language throughout the Bible.
Greek, Jewish, etc

that paired with what God can do or will do or who He is, makes a compound name of description like 


  Yahshua Ha Mashiach is "Jesus the Messiah."


or 


  Jehovah Rapha (The Lord who heals) 


they are all names for the same God, to better describe who He is and what He does.

there are many compound names for Him throughout the Bible.


Elohim or El "Strong One"
Yahweh (YHWH) "to exist, be" {see Link below}
Adonai "Master, Owner"
Theos Greek Translated "God"
Kurios Greek Translated "Lord"
Despotes Greek Translated "Master"
Father


of which many Compound names are given


El Shaddai "God Almighty"
El Elyon "The Most High God"
El Olam "The Everlasting God"


And


Yahweh Jireh (Yireh) “The Lord will provide.”
Yahweh Nissi “The Lord is my Banner.” 
Yahweh Shalom “The Lord is Peace.”
Yahweh Sabbaoth “The Lord of Hosts.”
Yahweh Maccaddeshcem “The Lord your Sanctifier.”
Yahweh Ro’i  “The Lord my Shepherd.”
Yahweh Tsidkenu “The Lord our Righteousness.” 
Yahweh Shammah “The Lord is there.”
Yahweh Elohim Israel “The Lord, the God of Israel.”


there are many more than just these, but the resource that I used is a Website

The Names of God

it explains slightly better than I have and gives more insight into some of these names.

Really these Names are just descriptors of God