1. A tag recommendation system comprising: a computing device; a tag selection element implemented at least in part by the computing device and configured for selecting a plurality of candidate media/tag pairs wherein a candidate tag of each of the candidate media/tag pairs exhibits raw co-occurrence with a target tag of a target media/tag pair; a tag co-occurrence normalization element configured for processing each of the plurality of candidate media/tag pairs against the target media/tag pair resulting in corresponding tag co-occurrence (“TC”) relevance measures wherein the TC relevance measures are in a semantic domain; a visual language modeling element configured for generating a candidate visual language model (“VLM”) for each candidate tag of the plurality of candidate media/tag pairs and a target VLM for a target tag of the target media/tag pair, and further configured for processing each of the candidate VLMs against the target VLM resulting in corresponding tag content correlation (“TCC”) relevance measures wherein such relevance measures are in a visual domain; a visual correlation element configured for processing each of the candidate VLMs against the target VLM resulting in corresponding image-conditioned tag correlation (“ITC”) relevance measures wherein the ITC relevance measures are in a visual domain, wherein the ITC relevance measures are based at least in part on a distance between the target tag and at least one candidate tag, and wherein the distance is an asymmetric distance or a symmetric distance, and wherein the asymmetric distance defined as D ITC a ⁡ ( t i , t j , x ) =  L t i ⁡ ( x ) · L t j ⁡ ( x )  L t i ⁡ ( x )  - L t i ⁡ ( x )  where x is a target media instance of the target media/tag pair, and where L t i (x)=[ , ], and wherein the symmetric distance defined as D ITC s ⁡ ( t i , t j , x ) = L t i ⁡ ( x ) · L t j ⁡ ( x )  L t i ⁡ ( x )  ⁢  L t j ⁡ ( x )  where x is the target media instance, and where L t i (x)=[ , ], and, for both the asymmetric distance and the symmetric distance, where exponents of 1 indicate a unigram likelihood based on a VLM in a unigram form, and where exponents of 2 indicate a bigram likelihood based on a VLM in a bigram form, and where exponents of 3 indicate a trigram likelihood based on a VLM in a trigram form; and a multi-domain combining element configured for combining one or more TC tag lists indicated by the TC relevance measures with one or more TCC tag lists indicated by the TCC relevance measures and with one or more ITC tag lists indicated by the ITC relevance measures, and further configured for forming a list of recommended tags from the combined one or more TC tags and the one or more TCC tags and the one or more ITC tags.
8. The system of claim 1 wherein the distance is defined as the inter-product of two likelihood vectors.