"Life is just one damned thing after another."
-- Elbert Hubbard (1856 - 1915)
The phrase "One Damn Thing After Another" has a long and somewhat cultured history. It has been quoted by well known authors, been bandied about by the upper class in English gentleman's clubs, and generally been one of the more appropriate ways of using the word 'damn' in polite company. At some point during the Victorian period it became common to abbreviate it as ODTAA; this initialism was probably cemented firmly in the public consciousness with the publication of John Masefield's 1926 novel ODTAA. It has since been used by other authors, musicians, and web-designers for various purposes.
Perhaps the most useful usage of ODTAA is found in the realm of writer's workshops, where it is used to refer to a common plot formula, one which dates back at least to the Roman playwright Terence, and arguably even earlier. A story with this formula doesn't build to a conclusion so much as it relates a series of adventures or happenstances. First something happens, and then it is resolved; then something else happens, and it is resolved; then something else happens... It's just ODTAA.
In the Turkey City Lexicon this is called an 'And Plot'. This type of plot is very, very, very common in bad science fiction, so it's not surprising that they have a term for it; it is somewhat surprising that they have a different term for it. Lawrence Block, in his book Telling Lies for Fun & Profit, uses the phrase 'one damned thing after another' to refer to this sort of plot. Dennis O'Neil, the author of The DC Comics Guide to Writing Comics uses the short form, 'ODTAA', as does literary historian Elliot Engel. In just about every genre other than SF/F it is known as an ODTAA plot.
While authors are generally warned away from this sort of story, the ODTAA format does not always result in a bad story; they are historically closely identified with the picaresque novel, from the Iliad onwards. Don Quixote, along with the early works of Charles Dickens and many works of Henry Fielding have an ODTAA-type format. Travel documentaries, biographies and other non-fiction works also generally follow this format, because that's just the way life is.
"It's not true that life is one damn thing after another; it is one damn thing over and over."
- Edna St. Vincent Millay (1892 - 1950)
ODTAA also stands for the Organ Donation and Transplant Association of America