Ben Poole: Blog, articles and tips related to Lotus Notes/Domino application development.
Codestore: Daily Blog and collection of articles, tips and sample applications for developing Domino web applications.
Cycom Inc.'s Lotus Notes Resources: Links, tips, and tricks for developers.
Documentaal - BowTie: BowTie is an integration tool for Lotus Notes and MS Office
Domino Guru: Blog, articles and tips for developers on Lotus Domino and related technologies.
IBM Redbooks Home Page: IBM redbooks related to Lotus Notes and Domino are available here for download as Adobe Acrobat PDF files.
Johan Känngård: Blog and articles for developers on Lotus Domino, Java, LotusScript and web.
Lotus Notes Programming Forum: Discussion on programming issues. Forums on lotusscript, formula language, agents, and Java.
MadJunk: Lotus Domino Administration articles, tips, and topic discussions.
Martin Scott Consulting: Domino SuperSearch. Search 30+ Notes/Domino technical knowledgebases at once. Notes code library and technical whitepapers.
NotesDesign: Development tips and techniques, information, downloadable example databases, and links to related sites.
Notestips: Articles, tips and discussion for developing web applications, using web standards and Lotus Notes and Domino. Daily weblog and discussion topics.
OpenNTF: Provides applications for Lotus Notes as open source, which may be freely distributed.
TeamStudio: Provides a series of tools for Notes/Domino development. Company information and downloads.
The View Magazine: "The Technical Journal for Lotus Notes and Domino" In depth articles for developers.