I think for search purposes it would be nice to add "synonyms" to expand abbreviations or provide other means to find the node. (Probably an R person might find the Concatenate nodes more easily with the rbind search expression, while the dendrogram might be easier found if it were associated to hiearchical clustering view.) I know similar thing can be achieved using categories, but why should we create more deep hierarchy than necessary? (Also probably indexing -and an option to search it too- the content of node descriptions would be nice. Have you tried finding the nodes that can provide medians? Yeah, I am looking at you Box Plots. :-) I hope the demoed KNIME Search will provide help in this reagard too.)
I know this could be overused, for example if a developer adds "spam" tags, but hopefully the users can decide whether they want/need certain extensions (and for community contributions -at least the trusted ones- could be monitored more closely).