GloBIS/GART was a initiative to provide access to general information about butterflies on the basis of a global taxonomic catalogue. It started in 1998, and by 2005 completed a global checklist of Pieridae and Papilionidae of the World. Web page last updated in 2011.
The Global Lepidoptera Names Index 209,000 names. Database last updated in 2005.
Butterflies and Moths of the World (by Brian Pitkin and Paul Jenkins, Natural History Museum of London), aimed to compile a comprehensive interactive catalogue of all the published genus-group names of Lepidoptera. Last updated in November 2004.
The Taxome project aims to coordinate the production, completion, and dissemination of online taxonomy of Lepidoptera on our planet at the species and subspecies level. It started around 2002, and was actively funded between 2004 and 2006. It completed taxonomic checklists for ~75% of all butterflies. It provides regional checklists for the Neotropics, Afrotropics, Nearctic (provisional), Australia and the Palearctic (partial), as well as global checklists for the families Pieridae and Riodinidae, and the subfamily Lybitheinae, and also for all butterfly genera.
Lepidoptera and some other life forms is a private project by Markku Savela. It provides a taxonomical tree structure with compiled information on names, distribution and hostplants, well documented with several references and links to available content in other sources. The main structure was last updated in 2008, although some content seems to be updated recently.
Nymphalidae.net by Niklas Wahlberg and collaborators.
Butterflies of the Americas: 160,500 images and list over 8,300 species fotographs of type specimens, uses an updated version of the Neotropical and Nearctic checklists from the taxome project.
Tropical Andean Butterfly Diversity Project based on a similar version of the Neotropical Checklist