Agglomerative Clustering - Dendrogram Labels

I would like to request of showing the labels (id) on the dendrogram leaves (have an optional possibly through a checkbox) when viewing the results of the analysis. It is understandable that for large datasets this may not make much sense because of too many leaves to be labeled. However, for small to medium size datasets, it is very useful to understand the resulting clusters by viewing the observations in each branch. What would be even better is the ability to interactively change the threshold to show a horizontal line indicating the clusters. This feature would be of much help in interpreting the results from hierarchical clustering analysis. Thank you.