I used 10D(2003-2005), 1D Mark2 (2005-2008) and currently a 40D (2008 onwards)500mm L USM f4.5 lens( 2003-2006) 600mmf4 L USM (2007...) with Kenko Pro300 1.4x or Canon 1.4XEF or Canon 2x converters. The lens is always mounted on a Gitzo1349 Carbon Fibre and full Wimbereley (gimbal) head. EF100-400mmL f4.5-5.6IS- Bought on 2008 for a more versatile lens.
90% of my gear are bought 2nd hand (used) to save cost.
10D- My 1st DSLR. With this introduction from Canon, I decide to switch from my Minolta system to Canon's. At that time, this is a mid-range camera capable of shooting various subject including action. Although the success rate is lower, it is still useful with much practice.
1Dmark2- My 1st professional DSLR, capable of shooting high speed subjects with the help from it's fast auto-focus system and 45 AF-points. Very solid in bulit. Although it is now replaced by 1Dmark2N and mark3, it is still a camera I have not out-grown it.
40D- Much improved since 10D's days. AF speed is fast although still not as intelligent as 1D's series.
500mmf4.5 L- A old 500mm auto-focus lens. It is using a ring-type USM. The main advantage of this lens is the light weight. Weighing less than 3kg. It is very mobile. Some flight shots are able to be captured by handholding this lens. It is a very sharp lens when used properly. However I decided to change to a heavier 600mm f4(Non-is) due to it is not so useful when coupled with a 1.4x converter. With a 1.4x, it auto-focus with 1 point with my 1D DSLR. The latest 500mm F4-IS is a much useful tool.
600mmf4L (non-is)- Although heavy(6kg), the resulting image is much pleasing than the 500mmf4.5 due to the extra 100mm reach. With a 1.4x, the result are even better. Although it is longer than 100mm, the resulting image is larger by 30-40% which is important for bird photography. Also, I can still use the 45points AF with a 1.4x converter. I felt I can get sharper pictures than the 500mm4.5 due to the weight which helps to stabilise the vibration inherent from long lens. Of course my dream is the latest Canon 600mm IS. Sold in end 2008.
Macro- 40D, Canon180mmf3.5L and Manfrotto 190cxPro3.