SDExpo (http://www.sdexpo.com)
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Lots of software tool vendors. Organized by the same company that produces the magazine Software Development.
Emerging Tech (http://conferences.oreillynet.com/etcon)
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A general technology conference, but with some good presentations on different tools and their technologies.
LinuxWorld Expo (http://www.linuxworldexpo.com)
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Obviously specific to one operating system, but with lots of speakers who are experienced software developers and toolsmiths.
ICSE (http://www.icse-conferences.org)
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International Conference on Software Engineering, organized by the ACM and IEEE. Mostly papers from academia, but useful for seeing what ideas other people have already investigated.