Utilities:

• FTP: Cyberduck, Transmit, FileZilla.
• Text, GUI: Smultron, Notepad++, CLI: nano, Aquamacs, MacVim.
• LaTeX: MacTex, Lyx.
• File compare: Unison.
• Windows PDF: Foxit.
• Browsers: Firefox, Camino, Chrome, and Safari.
• Mail: I mostly use Mail.app, but Thunderbird would be my second choice.
• Video Players: VideoLAN, MPlayer.
• Office: OpenOffice. I keep hoping for a cocoa version of Gnumeric like AbiWord or Bean.
• MySQL management: Sequel Pro.
• FinkCommander (and, of course, Fink). On the other side, MacPorts.
• 3D: check out blender. For compositing, Jahshaka and Cinelerra are promising, yet both have a bit to go.
• Paint: The Gimp has come a long way, and I like the UI/look of v2.4. Mac Gimp builds, working on ditching X11. CinePaint is based on an earlier branch, designed for frame-by-frame touchup. Shareware: GraphicConverter.
• Audio: try Ardour or Audacity.
• It’s hard to explain exactly what Quicksilver does (a GUI CLI?), but once you start it becomes habitual quickly.
• Nothing matches the elegance of HandBrake for DVD conversion.
Video conversion: VideoMonkey, TranscoderRedux. Trickery: ffmpegx, Mpeg Streamclip.
• Subtitles: Jubler, Subtitle Workshop, Subler.
• KStars, Celestia, Stellarium and Google Earth let you explore the universe.
• Network: port shaping, throttled, monitoring: ntop, wireshark; ipfw configuration: Waterroof.
• Wireless stumblers, kismac, iStumbler.
• Linksys WRT-54g Firmware: Tomato, DD-WRT, OpenWRT.
• DNS trickery: DynDNS, Tor.
• BT: transmission, wtorrent.
• Screenwriting: Celtx.
• Layout/SVG: Inkscape, Scribus.
• Ebook management: calibre. CBR reader: Jomic.
• Moving an OSX install, Carbon Copy Cloner.
• IRC: X-Chat, ircle.
• RSS Agregator, NetNewsWire, Vienna.
• HTPC: XBMC, Sapphire, boxee, MediaPortal, MythTV.
• NAS, FreeNAS, OpenFiler, Nexenta. Alternate file systems: MacFuse.
• Disk Partitioning, GParted, visualization: GrandPerspective, WinDirStat, defrag: MyDefrag.
• Compression: UnRarX, 7zX.
• System Emulation, Virtualbox, Q/QEMU.
• System stats: MenuMeters.
• VNC: Windows: TightVNC. Mac: I used to use Chicken of the VNC but now I mostly use Leopard’s built in utilities.
• My current x11 window manager is actually fluxbox, but it drops easily into either gnome or KDE. Cool beans: KDE/Mac.
• Some games.