• Winesearcher is a brilliant resource that allows you to search for a particular wine through the lists of thousands of merchants worldwide. There's a pay version that's worth the small premium.
• Tom Cannavan's wine-pages.com: a professional, comprehensive UK-based site that is updated daily. Hosts an active wine discussion forum.   
• Jancis Robinson is increasingly focusing here attention on her impressive website. With a pay-to-view section, Purple pages, but there's enough free stuff to make this worth visiting.
• Robin Garr's wine lover's page is a large US-based wine site with varied content, but I go there for the excellent Wine Lovers Discussion Group.
• www.eRobertParker.com is a pay site which contains an archive of Robert Parker's tasting notes and ratings. Parker is undoubtedly the world's most influential fine wine critic. It's also the new home of Mark Squires' bulletin board, a good place to discuss wine online. 
• http://www.finewinemag.com/ is the online home of the brilliant World of Fine Wine magazine. You should be subscribing to it.
• http://www.grape.co.za/ is the best way of keeping up with what's going on in the South African wine scene. 
• Chris Kissack's site, the winedoctor is regularly updated and well written. UK-based.
• http://www.nanson.ch/ is the online presence of Burgundy nut Bill Nanson, and ex-pat Brit now working in Basle. Useful and well put together. Bill also authors the superb burgundy report. 
• Fiona Beckett is a food and wine journalist with her own website devoted to matching the two: www.matchingfoodandwine.com. 
• Neal Martin's http://www.wine-journal.com/ was a great site - so much so that Neal was hired by Robert Parker as a wine critic at large, and so this site will continue only as part of Parker's subscription website. You can still find Neal's pages for free using one of the internet's archives, such as the way back machine. 
• http://www.flavourpress.com/ is my nascent wine book publishing venture.
• http://www.wine-science.com/ a site designed to complement my Wine Science book.
• http://www.wineint.com/ is the online home of UK consumer/trade magazine Wine and Spirit. Lots of good material here.
• http://www.decanter.com/ is UK magazine Decanter's website. Editor Adam Lechmere has developed it into probably the world's best site for wine news. 
• http://www.harpers-wine.com/ is home of UK wine trade mag Harpers.
• www.mitchell-beazley.co.uk the world's leading wine book publishers; website needs a bit of an overhaul though. As does their current wine offering.
• University of California Press publishers of my Wine Science book in the USA.
• Wine Business International is a trade title launched in September 2006.
• http://www.belmaati.com/ is musician and serious wine nut Joe Belmaati's growing community of fine wine lovers.
• http://www.finewinediary.com/ contains the collected tasting notes of British-based wine-loving brothers Richard and Toby Bailey. It represents an extensive, searchable collection of fine wine notes. The UK's answer to Frasier and Niles?
• www.onwine.com.au is well-known Aussie wine critic Jeremy Oliver's site
• The Cephas photolibrary contains Mick Rock's excellent wine photographs. 
• UK drinks writer Jim Budd has put together an impressive resource detailing the rogues and swindlers who encourage people to invest in drinks, at http://www.investdrinks.org/. 
• UK publisher and drinks writer Robert Joseph's venture, http://www.corkwatch.com/, is a forum for sharing information on cork taint. In his own words, he had become 'confused, bored and exasperated by the claims and counter-claims made by manufacturers of traditional corks and by some of those who advocate a switch to plastic, screwcaps or other forms of alternative closure.' 
• The Pinotage Club, a site devoted to this South African varietal, is certainly aiming at a niche market! It is an excellent site and well worth a visit.
• www.awri.com.au is home of the excellent Australian Wine Research Institute
• Another important wine science site is the UC Davis department of Viticulture and Enology
• www.superplonk.com is the online home of ex-Guardian wine columnist Malcolm Gluck and author of the popular annual wine guide.
• http://www.westcoastwine.net/is home to Brad Harrington's US-based discussion board. It also hosts an Italian wine forum.
• Although the Australian Wine Centre, http://www.auswine.com.au/, is predominantly an e-commerce site, it does host the excellent auswine discussion forum.
• New Zealander Anthony Hawkins has built an impressive glossary of wine grape varieties: http://www.lincoln.ac.nz/v&o/grapglos.htm
• TBM's Wine Links is a useful wine link list: http://beam.to/tbm.
• www.allaboutwine.com is an extensive directory of wine-related links, nicely arranged.
• Strats place is a large US-based collection of wine-related material, including label images and a forum.
• http://www.janetprice.co.uk/: an impressive UK-based wine photolibrary.
• http://www.greekwinemakers.com/ is a superb resource for anyone interested in Greek wine, run by Nick Cobb
• http://www.drvino.net/ the self-styled US-based Dr Vino gained a PhD in the economics of wine, and this site has a mix of features and recommendations
• http://www.quaffersoffers.co.uk/ is a new site that serves bargain-hunting Brits.

See also: my online directory of UK wine merchants and directory of wine accessories cellar solutions and holidays which include links to the best places to buy wine and wine-related items in the UK.