LOLmacros have undergone an Explosion event, wherein they have crossed over into commercial culture. When this happens, the community which spawned the meme subsequently declares the meme dead at the same time that commercial media declares the meme alive - I call this the Maxwell's Demon Indicator (MDI). The MDI comes into play every time an underground punk band goes mainstream.
The primary reason for the LOLmacro's success is due to, in my estimation, the meme's high rate of mutability. Mutability is determined by how much alteration a meme can undergo and still be recognizable as representative of the meme.
I have devised a way to measure this mutability that I call the Novelty Index.
Here is how it works:
Novelty Index (NI) = Number of points of alteration / Total points in the meme (each word/picture/gesture counts as one point)
This requires an in-depth example:
Consider the meme "All your base are belong to us."
This takes the general form "All your [noun] are belong to us." Replacement of the noun is the most accepted alteration. While changing the verb might still lead to recall of the meme, tolerance of this variation is considered too low to qualify. Therefore, the Novelty Index is 1/7.
As the NI approaches a 1:1 ratio, the longevity of the meme increases. The Novelty Index is never greater than 1:1.
A meme with more total points will have a lower rate of transmission. Simpler is better.
Type Acceptance (TA) is the number of possible elements that can be utilized in a modify point. Suppose it were acceptable to write "All your [verb] are belong to us." The modify point would then accept [noun] and [verb], two separate elements.
A simple one-dimensional categorization of TA can be found by multiplying the number of points of alteration by the number of possible elements. For the original All Your Base example, 1 x 1 = 1.
A higher TA not only increases longevity but increases the chance that a meme will spawn a new subtype.
To sum up, All Your Base has an NI of 1/7 and a TA of 1. With only 7 total points, its transmission rate is high, but its longevity is quite low. This is a meme that saturates quickly but holds no long-term amusement value.
Note the "i'm in ur base, killin ur d00ds" as diagrammed by Anil Dash has an obviously higher NI.
When classifying elements one must keep in mind the subset. LOLmacros are the parent set of image macros that utilize altered leetspeak, as noted by David McRaney in this post. Therefore, LOLcats is a subset that exclusively uses cat images. This specificity must be factored into any calculations.
As a case study, there are many crossover elements between (1)I CAN HAS CHEEZBURGER?, (2)Cute Overload, and (3)ytmnd. All three are heavily image-based yet dependent on text.
(1) is made up of elements that can be easily reduced to an automated process. However, the text must still conform to bastardized leetspeak and will no doubt be judged harshly if the phrasing seems inconsistent. While no unified grammar exists at this time, there are aesthetics which can be gained by exposure to examples - and like any specialized art community, whatever is accepted is what is acceptable, whatever is rejected is excluded from the set.
(2) is similar to lolcats, but it employs a baby animal as its centerpiece. Text is not deployed on the picture but in a post body, blog-style. Nevertheless, the text is a vital element in the overall composition. The speech employed can be either pedantic or an altered babytalk.
(3) has one of the highest NIs possible, as should be apparent by the number of new sites created every day. The front page explains the simple formula: "It stems from an idea that, using sound, and image, and some text, the users can convey a point, funny, political, or otherwise, to the general media." To be more specific, it follows the form [tiled image/looped video (often altered)] [sound loop] [splash text]. The NI is 3/3 (though it is acceptable to leave out the text) and a TA of 12. The challenge in creating a ytmnd is to link all three elements into a unifying concept, much like the creation of a punchline.
It should be noted that the mathememetic analysis detailed in the first part of this post utilizes very simple calculations.
There is a more advanced method for obtaining the TA, but it uses matrices to track points, possible elements, and acceptability in order to arrive at several limit sets.
But that requires Alolgebra.