I've improved the text here and there; the most important bit is a clarification of aspect. (If you have ALC, there's a whole section on aspect there; read that instead.) This blog post gives the essentials.
And while you're at the store, pick up my novel, Against Peace and Freedom.
All you could want to know about Verdurian is on the web; the language information is just part of that encyclopedia of Almean life, Virtual Verduria and even more at Almeopedia. There's a dozen or so languages there, each of which is doing something a little different.
You can meet other conlang enthusiasts— and get help when you're stuck— at the zompist bboard (ZBB).
There's plenty of interest to conlangers on my main page, zompist.com, including the Sound Change Applier, If English was written like Chinese, Hau to pranownse Inglish, the number from 1 to 10 in over 5000 languages, and When do people learn languages?.
Good reading on dead trees: see my list of recommended books for conworlders.
Last checked for linkrot in September 2011.
The Language Creation Society has a number of online resources, runs an annual conference, and has started up a conlanging journal. Their online links are probably more up to date than mine.
Rick Harrison has an elegant page with a respectable conlang, Vorlin, and a renunciation of IALs that IALers will dismiss at their peril. Esperantists will not like Justin Rye's critique of Esperanto, but for others it contains much to think about while constructing a language.
Richard Kennaway has many links to descriptions of conlangs and resources for creating them, and it's annotated (something not enough linkmeisters bother to do).
If you read French, see Christophe Grandsire's page of conlang reviews: meaty descriptions of quite a few conlangs.
Pablo Flores has some nice Tolkienesque languages, plus his own guide to language creation (based on this one).
If you're thinking of generating vocabulary by machine, take a gander at what Chris Pound has done.
The master of the secret vice is J.R.R. Tolkien, whose conlangery is lovingly annotated here. Don't miss the Harvard Lampoon parody.
See a bunch of constructed alphabets (including Verdurian), and contemplate supporting them with Unicode, at the
ConScript Unicode Registry.
Newsgroups: try alt.language.artificial. There's a number of mailing lists, such as Conlang, Auxlang, Tolklang, and k.d. lang, which were active as of 2009, at least.
If you're interested in constructing whole worlds, you might like
Juuha Vesanto's huge list of fantasy worlds (+), or
Geoff Eddy's guide to creating worlds, or
Patricia Wrede's list of questions for world creators.
Conworlding
Font creation
Several people recommend FontForge, which is free and powerful, but the user interface and installation process are said to be daunting.
FontStruct is free tool though its methods (fonts are constructed from "geometrical shapes... in a grid pattern") sound limiting.
FontLab has a number of products at various price points, including Fontographer; I used an early version for a number of Almean fonts. The cheapest is TypeTool for just $99.
FontCreator is another non-free editor, for Windows only; the Home version is $79. There's a free trial version.
The glossing rules in ALC will get you through most glossing situations, but the Leipzig Glossing Rules are the heavy-duty linguists' version.
As mentioned in the book, Kevin Russell's intro to acoustic phonetics is good.
Of certified interest to conlangers: the Language & Linguistics Museum on my board.