Sequoia
A practical guide, to this software development methodology, that helps the developer in every step of an IT project. Includes examples and links.
http://www.sequoia.be/consult/method/it_development_methodology.htm

Introduction to Thoughtful Programming and Forth Philosophy
By Michael Misamore; essay with text and references, on a flexible, proven, back-to-basics, minimalist philosophy that operates consistently from low to high abstraction levels; with ideas for future improvements. [Freely Distributable]
http://www.ultratechnology.com/forththoughts.htm

Osellus Inc.
Offers consulting and the IRIS software(based on SPEM) to automate and simplify the software development process. Includes white papers and links.
http://www.osellus.com/

Select Business Solutions
Provide modeling tools, component reuse, and service oriented architecture tools.
http://www.selectbs.com/

Alexandria
Composition-based product line methodology supports the flexible development based on product lines.
http://www.theoinf.tu-ilmenau.de/~riebisch/pld/

DSM Forum: Domain-Specific Modeling
Forum exists to spread the knowledge and know-how of Domain-Specific Modeling. Examples applying in industrial applications, events, publications, links.
http://www.dsmforum.org/

Methodology.org
General information, lists of papers, books, fora, links.
http://www.itmweb.com/methodology/

Methodology (Software Engineering)
Growing article, with links to many related topics. [Wikipedia]
http://en.wikipedia.org/wiki/Methodology_%28software_engineering%29

Waterfall 2006
International Conference on Sequential Development: Learn how slow, deliberate handoffs (with signatures) between groups can slow the rate of change on any project so development teams have more time to spend on anticipating user needs through big, upfront design. Humor.
http://www.waterfall2006.com/

Cleanroom Software Development Methodology
Introduction, overview, and examples; by John W. Shipman.
http://infohost.nmt.edu/~shipman/soft/clean/

OOAD, AOP and Design Patterns
Weblog on object-oriented analysis, design, processes, methodologies, design patterns.
http://object.motime.com/

Gatherspace.com
Offers hosted requirements management and use case software.
http://www.gatherspace.com/

Extreme Programming (XP) Six Sigma CMMI
JPMorgan Chase case study of how to use together the methodologies of XP, Six Sigma, and Capability Maturity Model Integration. Format: slide show on PDF.
http://www.sei.cmu.edu/cmmi/presentations/sepg05.presentations/jarvis-gristock.pdf

Object Orientation Tips
Articles on Methodologies in object-oriented design, Patterns, persistence, analysis and Use Cases, distributed objects, components and agents.
http://ootips.org/