RNAseq, the measure of abundance of transcribed genes at a particular cell state is one of the most common assays done with next gen sequencing. That's the big one then of course there is also miRs, transcription factors, methylation, histone marks, chromatin conformation capture.

As someone with a CS background who has worked almost 5 years in bioinformatics, one thing to realise is if you think something obvious is not done, either you're missing the right search term on pubmed or there's some horrible lab issue that makes it really hard (and we need a new assay/tech)