Some things I found to be useful for daily programming.

Programming

• Geany: very fast IDE, not the memory and CPU monsters out there like Eclipse/Netbeans.
• Valgrind: code analysis tool, I use mainly the memory checker and the profiler.
• KCachegrind: graphical profiler presenting runs of valgrind performance checks in a nice way.
• xxdiff: 2 and 3-way graphical diff tool, I use it because of nostalgia (aka: I got used to it).

C Programming

• Gengetopt: parser for command line options

Database Modelling

• dbmodel: a very neat database modeller with PDF and image export.

Data processing

• XMLStarlet: XML processing on the command line for fast and dirty XML processing

Infrastructure

• openSUSE Build Service: for building release packages in the cloud.
• Travi CI: for continuous integration on Mac OSX.
• Using libvirtd now instead of VirtualBox (sorry, Oracle). Main reason: it’s still a little bit un-ready round the edges but hey, it’s really open source. :-)
• LXC: lightweight and surely nicer to use than Docker (IMHO). Still a little bit alpha quality though.
• unison: file synchronizer, I’m using it since years to sync my home directory between three or four machines, sort of a very easy backup.
• The backup from the local LAN to the cloud happens via FTP and some copy jobs within Bacula.

Books

• The Pragmatic Programmer: an absolute must for every programmer.
• The Mythical Man-Month: an absolute must for everybody doing a project.
• AntiPatterns: Refactoring Software, Architectures, and Projects in Crisis: avoid mistakes by learing from bad examples.
  

Other

• Ion3: tiling window manager with strong keyboard and Lua scripting support. Sadly the original author got into fights with the open source community :-(
  I’m currently using the fork Notion.
  Read http://raboof.github.io/notion/tour/ if you want to learn how to use such a window manager.
• Joe: my editor for all quick editing jobs. Having used a lot of Wordstar in my youth, jstar is the editor I can’t get rid of in my brain. :-)
• meh: as fast and easy an image viewer can possibly get.
• MuPDF: an equally fast PDF/XPS viewer.
• Trojitá: a simplistic and really fast mail reader for IMAP accounts. For long-term archiving of email I’m using a combination of OfflineIMAP and good old Mutt.
• Seamonkey: back to old SeaMonkey, fast, no clue what they did to Firefox to make it so slow.