Genres

Science fiction and fantasy are huge genres, and there are a number of more detailed subgenres out there that can help people find the books they like. The Wikipedia entries on science fiction and fantasy are good starting points. Genres being fluid things, terms like hardboiled (wikipedia entry) that originated in crime fiction (wikipedia entry) are also relevant. There are also overlaps, such as science fantasy (wikipedia) overlapping SF and fantasy, and dark fantasy (wikipedia) overlapping fantasy and horror.

Cyberpunk (wikipedia) has had a great deal of influence through science fiction and fantasy, which can be seen in the New Weird (wikipedia) work of China Mieville and Alastair Reynolds, postcyberpunk (wikipedia) creations like Down and Out in the Magic Kingdom, Snow Crash, and Singularity Sky, and steampunk (wikipedia) like The League of Extraordinary Gentlemen and The Difference Engine.

Another subgenre of fantasy is fairytale fantasy (wikipedia), which includes retellings of classic fairy tales (such as Briar Rose and The Wild Swans) and the use of such motifs (as in The Godmother). A related genre is mythic fiction (wikipedia), such as Mistress of Spices, The Antelope Wife, and Anansi Boys. This latter category has a fair amount of overlap with the genre-crossing slipstream (wikipedia) work, which also includes The Hereafter Gang and The Calcutta Chromosome.

slothman,

I do a similar thing, but I tag my fairy tale retellings as "retelling" -- so that I can include things like, say, The Once and Future King (Arthurian myth), Tam Lin (ballad), and Wicked (The Wonderful Wizard of Oz) that aren't strictly fairy tales.

(I'll have to check your library for others to add to my collection!)

An interesting thing I just noticed that is probably related to the way we define subgenres, versus things that just happen: only three people of the 7,000 who own it, have tagged Harry Potter and the Prisoner of Azkaban with 'time travel'.

Maybe because the travel is such short distances. Maybe because by they time you've tagged all the harry potter books with fantasy, school story, mystery, wizards/magic, wainscot/hidden society, adventure, sports story, you aren't looking for extra tags for a particular book.

Dragonflight by Anne MacCaffrey also has only 4 time travel tags out of 700 owners.

I tag books only with the "main theme". The time travel in HPPA is a relative short period (if I remember correctly, it's been some time). The period is important, but not a main theme.
Make sure you check my tags, you'll find I'm a lousy one! But I think that is one of the main reasons why only three out of 7000 have tagged HPPA with timetravel.

There's lots. Space Opera which is how I'd describe Alistair Reynolds work rather than Cyberpunk.

I also use faery fantasy, urban fantasy, high fantasy, dark fantasy and SF crossover.

Al Reynolds would be New Space Opera in my book if I went down to sub-genre.

The Encyclopedia Of Science Fiction has a useful list of themes in the front (although not always sub-genres) that could also aid in tagging.