A 1915 article by Páll Eggert Ólason in the Icelandic literature journal Skirnir gives a description and examples of hiding words in Icelandic poetry using rune kennings. The article, Folgin nöfn í rímum (‘Hidden names in the rímur’) can be seen here: http://timarit.is/view_page_init.jsp?pageId=2009626 but I don’t believe I’ve seen anything related to this printed in English, except for a brief mention of the practice in R. I. Page’s edition of the Icelandic rune poem (which can be found here)
What are rune kennings? If you’ve read the Icelandic rune poem you may have noticed that each of the verses is an arrangement of kennings, not unlike any other used in skáldic poetry. For example:
Ís er árbörkur
og unnar þak
og feigra manna fár.
Ice is river-bark
and a wave’s roof
and a doomed man’s misfortune.
But there were far more than just three kennings for each rune. For some the supply could be nearly limitless – since the word maðr (‘man’) was both the name of the m rune ᛘ, and a very common word in skáldic poetry, it could be referred to in innumerable ways. Lists of runes with their kennings were hand-copied by Icelanders for hundreds of years in early modern times (an example from 1764: http://handrit.is/en/manuscript/imaging/is/IB04-0299/146v-148v#0146v)
Typically, stung runes — runes composed by taking a rune from the 16-character fuþark and adding a diacritic, such as ᛂ (e), ᛑ (d), and ᚵ (g) — did not pick up their own kennings, but shared them with the rune from which they were derived, and that it was stung would have to be specified separately. On the other hand, the runes ᛕ/ᛔ (p), ᚯ (ö), and ᛅ (æ) did pick up names and kennings (plástur ‘bandage’; ör ‘arrow’; ᛅ varies somewhat).
How do they work? Here are two strophes from Völsungsrímur. I normalized a bit from the Skírnir version. The English translation is very rough because the meaning isn’t important for this.
Fjóls blóma fegurð¹ sé
fýsir þangað ríða²
Sumir mæðast sorginni³
svellið springur⁴ víða.
(The beautiful blooming of violets* be
eager there to ride
Some are inflicted with grief,
ice breaks widely.)
Eikin blómguð⁵ aldin⁶ regn⁷
Óðins burinn hreldur⁸
úði⁹ sumar¹⁰ marsins megn¹¹
mæðir Hlýrnis eldur¹².
(The flowering oak fruit rain
Óðins grieved son
rain of summer the mare’s power
harms the heavens’ fire.)
Uppheims funi¹³ álfta grund¹⁴
ærinn harmur¹⁵ þjóða.
Marga girnir stytta stund
starfi meður ljóða.
(The sky’s flame, the ground of the swan
great harm to the nation.
Many desire to shorten
their work with singing (make the time it takes to do farm tasks seem shorter)).
You may have noticed that this doesn’t make any sense. What is oak fruit rain? Who is responsible for this?
The first question is unanswerable, I’m afraid, but the second can be answered with a close inspection of the poem. Each of the underlined words or phrases is a rune kenning, synonym for a rune name, or another indirect reference to a rune name.
1. fjóls blóma fegurð (‘beautiful blooming violets’) = ár (‘year/harvest’) A
2. ríða (‘to ride’) = reið (‘ride, vehicle, horse’) R
3. sorginni (‘sorrow’) = nauð (‘distress, need’) N
4. svellið springur (‘ice breaks’) = stunginn ís E
5. eikin blómguð (‘flowering oak’) = bjarkan (‘birch’) B
6. aldin (‘fruit’) = ár (‘year/harvest’) A
7. regn (‘rain’) = úr (‘rain’) U
8. Óðins burinn hreldur (‘Óðins grieved son’) = stunginn Týr D
9. úði (‘rain’) = úr (‘rain’) U
10. sumar (‘summer’) = ár (‘year/harvest’) A
11. marsins megn (‘mare’s power’) = reið (‘ride, vehicle, horse’) R
12. Hlýrnis eldur (‘the heavens’ fire’) = sól (‘sun’) S
13. Uppheims funi (‘the sky’s flame’) = sól (‘sun’) S
14. álfta grund (‘ground of swans’) = ós (‘river (mouth of a river)’) O
15. harmur (‘sorrow’) = nauð (‘distress, need’) N
The author of the poem has signed his name: Arne Bauduarsson (in the spelling of his time, now this would be written Árni Böðvarsson).
Páll Eggert gives plenty of other examples in his article. The hidden message is not always the name of the person who wrote it, but sometimes the name of the person it was written for, or something like that.
Rune poem verse from Matthías Viðar Sæmundsson’s Galdrar á Íslandi retrieved from: http://heimskringla.no/wiki/%C3%8Dslenska_r%C3%BAnakv%C3%A6%C3%B0i%C3%B0