Not surprisingly, different interpreters have reached very different (and often very colorful) conclusions as to what this prophecy is supposed to mean.  However, the main differences eventually boil down to which method of interpretation--historical-grammatical (literal), or allegorical (figurative)--the interpreter employs.  The more one spiritualizes passages by means of figurative interpretation the more subjective (and therefore more dubious) the conclusions become--this prophecy is no exception.  Even among the many who interpret with some degree of literalness, there are still disputes over word meanings and the degree of literalness which should be applied. 

Non-Christological Views

1. Liberal critical.  This view considers the book of Daniel to be a 2^nd Century forgery written long after the events actually occurred. All 70 weeks were fulfilled in events following the Maccabean persecution.
2. Conservative amillennial.  This view considers the "weeks" to be of an intentionally indefinite length--some period of time measured by the number seven. They conclude the duration has to be determined by other [subjective] means.
3. Orthodox Jewish.  This view considers the 70 weeks to have ended with the destruction of Jerusalem in 70 AD.  This is essentially the preterist view.

Christological Views

1. Amillennial view.  This view considers the 70^th week to immediately follow the 69^th, and therefore is historically fulfilled--ending 3-1/2 years after Christ's death.
This is the Roman Catholic view, and has historically been the predominant view of the Church since Augustine.
2. Futuristic view.  This view considers a necessary time gap between the 69^th and 70^th week (for reasons I will explain later), and a yet future fulfillment of events described in the 70^th  week. Only this view allows for complete literal fulfillment. [Daniel--The Key To Prophetic Revelation, Walvoord]