Lots of big nationals and international companies have separate pages to tweet about job opportunities.
Conde Nast – Vogue, Conde Nast Traveller, Glamour…
Get Me TV Jobs
Haymarket – Lots of specialist magazines including Autocar and FourFourTwo plus they organise lots of brand events like BBC Good Food Show and Clothes Show Live
How Do – North West Media Jobs
IPC Media – Marie Claire, Wallpaper*, NME…
Live Nation – PR, Events and Digital Marketing jobs
Wall Street Journal