144,000 People

Revelation does not specifically identify the 144,000 mentioned in Revelation 7 and 14, so my answer will have to be somewhat speculative.

I should begin by stating that I do not ascribe the visions of Revelation solely to the future, but think they were immediately relevant to John's original audience. They are relevant to us too, but I tend to shy away from any interpretation that does not have some relevance to John's original audience. Also, I do not believe that biblical prophecy must necessary come to pass as stated unless the prophecy spefically says that it will. Rather, biblical prophecy is fundamentally conditional, and God is free either to bring it to pass as stated or not to bring it to pass as stated (see for example Jer. 18:1-10). See Richard's Pratt's article on Historical Contingencies for an in-depth discussion of this idea.

As for a couple details regarding the 144,000, I don't think they are all virgins (see Rev. 14:4). Marriage (including marital sex) and children are a blessing, not a defilement. Rather, their lack of "defilement" may indicate that they are arrayed for holy war, and that in this preparation they have not slept with their wives (compare 1 Sam. 11:8-11). It may also indicate that they have kept themselves from idolatry (which often included religious prostitution). On a related note, I don't think they are all men. Literally they are all men, but I think they metaphorically represent a larger group (see below). The fact that they are all men lends support to the idea that they are arrayed for holy war (see also Rev. 13:7). In reality, however, spiritual holy war (such as that fought by the original audience) is fought by men, women and children. Thus, I think the men metaphorically represent men, women and children. Also, it seems that they are all true believers, not just church members.

Some I respect have suggested that they are a metaphoric representation of the true church (compare "bond-servants" [Rev. 7:3]), with their number being a metaphoric indication of fulness, not a real count. This is probably correct, as long as we recognize that they are "first fruits" (Rev. 14:4), which indicates that they are not the final church.

One problem with interpreting the 144,000 literally is the names of the tribes. Specifically, Dan is missing, and both Joseph and Manasseh are mentioned. Manasseh was Joseph's son. Old Testament tribal lists that include Manasseh also include the other half-tribe descended from Joseph, namely Ephraim. Since everyone who is in the tribe of Manasseh is also in the tribe of Joseph, the list is redundant and a regular count is rather impossible. This strongly inclines me to believe that the count is metaphoric. Add to this the extremely metaphoric nature of the whole vision and I'm rather convinced.

Are the 144,000 the same multitude mentioned in Revelation 7:9-17? If they represent the true church, then this makes sense. On the other hand, in the context of Revelation 7 the 144,000 are all Israelites, while the multitude in Revelation 7:9-17 is comprised of Israelites and many different types of Gentiles (Rev. 7:9). In Revelation, however, this may not really be sufficient to deny their equal identities. The phrase "after these things" in Revelation 7:9 may indicate a shift to a new vision, and this new vision need not maintain consistent metaphors with the preceding vision. Also, Revelation 7:14 ("these are the ones who have come out of the great tribulation") would seem to support a "true church" interpretation.

It may be significant that the 144,000 are not identified as men in chapter 7. This may indicate that they are of mixed genders and ages in chapter 7. I suspect that the 144,000 in chapter 7 may be the true church prior to and during the "tribulation" (an event close to the original audience), and that the great multitude may be the true church after that tribulation. This would indicate that the 144,000 were not only preserved, but also that they grew and evangelized during the tribulation -- they came out stronger than they were when they entered. The identification of these 144,000 as men in chapter 14 would simply be for the sake of emphasizing holy war.

Beyond these comments, however, I wouldn't want to say too much about their identity without doing a significant amount of research and study on them.