These are some of the most popular websites for downloading presets. The presets listed here are a mix of PV2012 (Lr4/5) and earlier (PV2010/2003), and I’ve split them into Free vs. Paid to help your search. If you know of any more that you think should be included, please let me know. Enjoy!
Free Presets
Lightroom Killer Tips (Matt Kloskowski)
Free Lightroom Presets (free sign up required)
Free & Paid Presets
Contrastly (discount code QUEEN20 for 20% off)
The Preset Factory – 25% off with LRQUEEN25
Only Paid Presets
Really Nice Images (film emulation… very good!)
There’s also a looooong list of less well known presets you might like to explore here too: ProPhotoShow