For SVN, I use...
... the SVN client built into Xcode, the free development suite that ships on the OS install media (and is downloadable subsequently). Though it's Apple software, so perhaps I'm missing your point.
Straying from the Apple/Microsoft/Adobe fold, glancing through my /Applications folder I use the following good (and cost effective) software:
• Cheetah3d, for 3d modelling
• Pixelmator, because I do sometimes do editing things, but don't need Photoshop
• VirtualBox, which needs no introduction
• Skype
• 0xED, a hex editor, for when I'm (ever more rarely) doing bits and bytes stuff
• IBM Lotus Symphony, but only at work because I have iWork at home
• Audacity, sometimes...
• Sound Studio, ...the rest of the time
• The Unarchiver, for access to 7zip, lxma, etc archives (and sit too, if I'm unarchiving from history)
• SOAP Client, when programming anything to do with SOAP
• Google Chrome
• Froq, for access to a remote SQL database
• Cyberduck, an excellent FTP client
• Flip4Mac and Perian, both codec packs for QuickTime
• Inkscape, but only sometimes because as a lazy (note: lazy) X11 app, the user interface is horrid
• Citrix Metaframe, for the obvious uses
• SolidWorks eDrawings, for viewing CAD images — though I think I used this exactly once for exactly one project
• Snapz Pro X, for screen recording
• Meshlab, which is a cross platform set of 3d mesh tools
• RapidWeaver, which is a web page designer for the lazy
• Taco Edit, for HTML editing otherwise
Though the Microsoft/Apple stuff in particular is excellent, and the Adobe stuff really very good.
I would guess from the general tone of your statement that games don't count and I'm not much of a gamer, but I also have World of Goo, the recent Monkey Island and Steam installed.