Here are a good set to start with. Each links to their description in BOL. Run them on your distributor:

sp_replmonitorhelppublisher: Shows high level summary of publishers. Run with no parameters to show all publishers.

sp_replmonitorhelppublication: Shows detailed information about publication status. Run with a single NULL parameter to show all publications.

sp_replmonitorhelpsubscription: Shows detailed information about subscription status.

To show subscriber status for transactional publications:

sp_replmonitorhelpsubscription @publisher = NULL, @publication_type = 0

To show subscriber status for snapshot publications:

sp_replmonitorhelpsubscription @publisher = NULL, @publication_type = 1

To show subscriber status for merge publications:

sp_replmonitorhelpsubscription @publisher = NULL, @publication_type = 2

There are more ways to filter what each procedure returns based on the parameters - just read the BOL entries for each.