Post your computer specs here!

Computer: Sony Vaio VGN-NW20SF_S
Laptop/desktop: Laptop
Processor: Intel Core 2 Duo, 2.20 GHz
Hard drive: 320 GB
RAM: 4GB DDR2, 800MHz
Graphics card: Intel Integrated HD Graphics
Screen size/resolution: 15 Inches, 1366 x 768 Resolution
DVD/CD/other drive(s): Standard DVD/CD Burner Drive
Operating system: Windows 7 Home Premium, 64 Bit
Ports: 3 x USB, HDMI, Firewire, VGA and other random ones.
Other info/features: Wireless, built in webcam, one touch web boot up button, quick display off button.
Age: 7 Months

Computer: Custom build
Laptop/desktop: Desktop
Processor: Intel i7 930 @ 4.00Ghz overclock
Hard drive(s): 1TB 7200RPM/250GB 7200RPM and 3TB 7200RPM/1TB 7200RPM external HDDs
RAM: 24GB @ 1600Mhz
Graphics card(s): ATI Radeon HD 5870 1GB
Screen(s) size/resolution: 2x 1366x768 Acer X193HQ
DVD/CD/other drive(s): 2x Hitachi DVDRW @ 48x
Operating system: Windows 7 Ultimate 64bit
Ports: 4x USB 3.0
Other info/features: eg Wireless
Age: How long ago did you get the computer? Around 1 and a half years ago

Computer: Custom
Laptop/desktop: Desktop
Processor: 3.2Ghz AMD Phenom II X6 1090T Black Edition
Hard drive(s): 7200RPM SATA 1TB HDD
RAM: 8GB DDR3 Cas Latency 7 1333mhz (RAM is usually CL9, but I got CL7 as it performs better rendering video, and CL7 1333mhz is faster and the same price as CL9 1600mhz RAM)
Graphics card(s): AMD Radeon HD 6850 GDDR5 1GB
Screen(s) size/resolution: 21.5'', 1920x1080
DVD/CD/other drive(s): Generic ASUS DVD I bought on newegg for 16 bucks.
Operating system: win7 home 64bit OEM. If you ever build a system, ALWAYS buy OEM windows. I was $70 or $80 cheaper at my time of purchase. Its the same as the non-OEM, but not in a shiny box.
Ports:

PCI Express 2.0 x16 2
PCI Express x1 4
PCI Slots 1
6 x SATA III 6Gb/s
surround sound audio portrs (the 6 colored ones =S)
PS/2 1
8 x USB 2.0
2 x USB 3.0
S/PDIF Out 1 x Optical, 1 x Coaxial

Other info/features: cheapo rosewill wireless adapter. It does what it was advertised to do.
Age: 7 months.

Computer: Dell XPS 8300
Laptop/desktop: Desktop
Processor: Intel Core i7 2600 @ 3.4 GHz
Hard drive(s): 2 x 1.5TB Hard Drives @ 7200 RPM
RAM: 12 GB DDR3 SDRAM @ 1333MHz
Graphics card(s): AMD Radeon 6950 2GB DDR5
Screen(s) size/resolution: Dell 23 inch 1920 x 1080 LED
DVD/CD/other drive(s): Blu-Ray Combo Drive
Operating system: Windows 7 Home Premium
Other info/features: Wireless Card, Sound Blaster X-Fi Xtreme Audio Sound Card
Age: As of December 2011

Updated to reflect the changes back in December / January.

Computer: Custom
Laptop/desktop: Desktop
Processor: AMD Phenom II X6 1090t Black Edition 3.2Ghz (stock clock specification) (OC'ed to 3.6GHz for daily use)
Hard drive(s): 7200RPM SATA III 1TB HDD
RAM: 16GB DDR3 @ 1333mhz
Graphics card(s): AMD Radeon HD 6770 w/1GB GDDR5 vRAM
Screen(s) size/resolution: 1280x1024 TFT LCD + 1920x1080 LED backlit LCD
DVD/CD/other drive(s): None
Operating system: Windows 7 Professional x64
Ports: Check specs on the motherboard listed below.
Other info/features: ASRock 970 EXTREME4 AM3+, XIGMATEK Gaia SD1283 CPU Heatsink + 2x 120mm 110CFM fans in Push/Pull config, ASUS PCE-N13 b/g/n Wireless Adapter, Xigmatek ASGARD II case, XFX branded HD 6770, NZXT Fan Controller to quiet things down.
Age: Built July 29, 2011

Also, I've built a CustoMac Mini:

Computer: Custom CustoMac Mini 2011
Laptop/desktop: Desktop
Processor: Intel Core i3 2105 @ 3.1Ghz
Hard drive(s): 1 x 500GB 7200RPM
RAM: 8GB DDR3 @ 1333mhz
Graphics card(s): Intel HD 3000 (integrated on processor)
Screen(s) size/resolution: 1280x1024 TFT LCD + 1920x1080 LED backlit LCD
DVD/CD/other drive(s): None
Operating system: OS X Lion
Ports: Check specs on the motherboard listed below.
Other info/features: Low-noise Scythe Slipstream Case fan (poor ventilation in the case ), Rosewill b/g/n wireless adapter, Gigabyte GA-H61N-USB3 motherboard, APEX MI-100 Mini-ITX case.
Age: Built January 3rd, 2012
Currently dual-booting with Windows 7, though 99% of the time I'm on the Mac. If I want Windows, I'll use my better desktop.

Computer: iMac (main computer for everything except games and flight sim)
Laptop/desktop: Desktop
Processor: Intel Core i7 2500 at 3.4GHz
Hard drive(s): 256GB SSD for OS and programs, 1TB spinning storage disk.
RAM: 8GB DDR3-1333MHz
Graphics card(s): AMD Radeon HD 6970M 1024MB
Screen(s) size/resolution: 27" IPS Display at 2560x1440; LG 23" 1920x1080
DVD/CD/other drive(s): Standard DVD Burner/Reader
Audio: Built in iMac speakers (actually decent)
Operating system: Mac OS X Lion 10.7.4
Other features/ports: 4x USB 2.0; 2x Thunderbolt, 1x Firewire 800, Ethernet, Audio in/out, power.
Age: Almost a year.

Computer: Homemade
Laptop/desktop: Desktop
PSU: OCZ 550W ZT Modular
Motherboard: Asus P8Z77-V Pro
Processor: Core i5 3570k at 3.4GHz
Hard drive(s): 120GB OCZ Solid 2 SSD, 1TB WD Caviar Black, 500GB Segate 7200RPM, 1TB WD Caviar Green via eSATA used for archives.
RAM: Kingston HyperX 8GB DDR3-1600MHz
Graphics card(s): EVGA GeForce GTX 460 1GB (this will be the next upgrade, to a 670 when I find one on sale at < $300)
Screen(s) size/resolution: LG 23" 1920x1080
DVD/CD/other drive(s): Blu-ray reader (includes DVD/CD write)
Audio: Logitech Z623 2.1 Speakers; Logitech Clearchat Comfort Headset
Operating system: Windows 7 Home Premium 64-bit
Other features/ports: 8x USB 3.0, 10x USB 2.0 (vast majority of these are available by board header, 6 in total on back, 4 USB 3.0, 2 USB 2.0), eSATA/USB add in card for an extra 2 USB 2.0 and an eSATA port, optical audio out, HDMI, DisplayPort, VGA, DVI, Ethernet, PS/2 connector, 2x Firewire 400 (via add in).
Age: Built as an upgrade to improve X-Plane performance end of May 2012.
Other info: This one also supports the Asus Thunderbolt add in card that was just released so in time I will add Thunderbolt capability. That's also why I went Asus rather than my typical Gigabyte.