Numa and Egeria [good stuff!!]:
Same this, different page:

A tad about Egeria in relation to Numa:
    These are the notes that are important [the second is of particular note]:
    "- Water nymph Egeria aided him in his religious reforms"
    "- At his death, Ovid says Egeria flew to Aricia to grieve for the king, and there was rebuked by Hippolytus for disturbing the rites of Diana with her lamentations"

Numa's religious changes:

An illuminated text is found to be about Numa and Egeria [picture!]:
    click on "Apollo?" for the picture of what is most likely Numa and Egeria

Interesting couple little stories involving Egeria [search the page for the name]:

Similar recounting of one of these stories:

Blurb on Numa Pompilius [said to be pronounced noom pompils]:

Short blurb on the myth:

A little blurb on Numa and his "hydromancy":

Very interesting description of a fountain named after Egeria.  Might try to fnid photos of it:

Interesting info that Egeria was entirely a myth made up by Numa:
    No other info that I have backs this up, however

Includes a couple interesting poems about her:
    Byron, in "Childe Harold," Canto IV., thus alludes to Egeria and her grotto:

          "Here didst thou dwell, in this enchanted cover,
          Egeria! all thy heavenly bosom beating
          For the far footsteps of thy mortal lover;
          The purple midnight veiled that mystic meeting
          With her most starry canopy;" etc.

     Tennyson, also, in his "Palace of Art," gives us a glimpse of the royal lover expecting the interview:

          "Holding one hand against his ear,
          To list a footfall ere he saw
          The wood-nymph, stayed the Tuscan king to hear
          Of wisdom and of law."

This has a lovely painting of water nymphs:
            a. Numa claimed to meet with a goddess by night, Egeria
                    i. told what rites the gods approved
                    ii. which priests were to do which duty

Discussion of the fountain that Egeria and Numa were said to have met:

Another photo of the Egeria fountain: di Egeria

Mirriam-Webster definition [enter "Egeria", also includes pronunciation]:

Another dictionary definition:

Other references to Egeria, not related:

An aquatic plant:

A German bathrobe company:

A minor planet: