One of my CARR-line surnames is GIB. It didn't take any time at all to find that it could just as well appear in records as GIB or GIBB or GIBBS. Well, that's when it appears...it seems to be fairly rare, or at least it is where I've been looking! (East Riding of Yorkshire, 1770s)
Recently I picked up my Genealogical Research in England and Wales, Vol. 1, and I decided to see if the "Surnames -- Given Names -- Dialect" chapter had anything interesting. That's not a topic that ordinarily excites me...and I've probably never looked at that chapter before. First, I was surprised when I came to the name GIBB, and secondly, I was surprised to see a whole half paragraph!
Some variations in the spelling of surnames caused by local pronunciation are somewhat obvious, but others are not. ... A family of Gibb from near Chard in Somerset is found recorded under the spellings of Geeb, Geep, Gabe, and Geab. One interesting case is that of Betty Geab recorded in the 1851 census, whose death was subsequently registered and appears in the indexes at Somerset House under the spelling of Gabe. Although her burial at the parish church of Merriott is written Elizabeth Gibb, it was not until every entry recorded in the week of her death at the local superintendant's register office was checked, that the spelling Gabe was discovered. 
I wonder if I've missed any of these variations in my research? I think I would have made note of these, given how rarely I see any one-syllable word starting with G, but I will certainly pay more attention now!
- I found this book in a used book store in Utah several years ago. I think older books about research ofter have a lot to offer. And, re-reading them occasionally can be useful!
- I've added these unusual variations to my GIBB family group sheet so that I'm more likely to be reminded to be creative in my searching.
SourceDavid E. Gardner & Frank Smith. Genealogical Research in England and Wales, Vol. 1. Salt Lake City: Bookcraft Publishers, 1956, p. 273. [The italics are as they are in the original; the color is my addition.]