PC Gamer UK has a Battlefield 3 server! It supports 64 players! And fun! To get involved, just click here , or search for "PC Gamer" in the server browser. It's a Conquest-only affair at present, with every map enabled apart from Operation Metro (because everyone hates Operation Metro). The server is based in the UK and hosted by the lovely guys at Multiplay .
European players unite! There will be a US equivalent going live in the near future.
Let us know any tweaks you'd like us to make to the server in the comments. We'll definitely read your suggestions, and possibly implement them. Hooah!