There's a lot of neat small x86 stuff, but a lot of it depends on whether you're going low power or not.
If what you want is something like a Mac Mini but w/ higher end i7's your options are some Intel NUC or Gigabyte BRIX's which will be significantly more expensive than a baseline 2014 Mac Mini (but a bit cheaper when you match high-end RAM/SSD) - no TB2 or OSX (some ugly Hackintosh hacks withstanding) though. Gigabyte's BRIX Gaming is interesting since it has a GK104M based "GTX 760," which is amazing for the form-factor, but the trade-off is in relative cost and jet turbine fans. (The Alienware Alpha, Zotac EN760, and Asus GR8 are other "smallish" devices w/ dedicated GPUs).
You can get some really cheap/small Celeron-based NUC-sized machines (~$150 bare-bones) and throw in RAM/SSD for a very nice low-power Linux system. We use a lot of these at work at the moment, these are great.
Most of the fun stuff going on is with low power Bay Trail processors. Zotac has the C-series, which is between a NUC and Mac Mini in size, but also a Pico series (PI320) which is tiny, much smaller than the ECS Liva or the Minix Neo Z64 (which are also tiny). Also, there's the MEEGO-T01, which is the first Bay Trail HDMI stick I've seen.
If what you want is something like a Mac Mini but w/ higher end i7's your options are some Intel NUC or Gigabyte BRIX's which will be significantly more expensive than a baseline 2014 Mac Mini (but a bit cheaper when you match high-end RAM/SSD) - no TB2 or OSX (some ugly Hackintosh hacks withstanding) though. Gigabyte's BRIX Gaming is interesting since it has a GK104M based "GTX 760," which is amazing for the form-factor, but the trade-off is in relative cost and jet turbine fans. (The Alienware Alpha, Zotac EN760, and Asus GR8 are other "smallish" devices w/ dedicated GPUs).
You can get some really cheap/small Celeron-based NUC-sized machines (~$150 bare-bones) and throw in RAM/SSD for a very nice low-power Linux system. We use a lot of these at work at the moment, these are great.
Most of the fun stuff going on is with low power Bay Trail processors. Zotac has the C-series, which is between a NUC and Mac Mini in size, but also a Pico series (PI320) which is tiny, much smaller than the ECS Liva or the Minix Neo Z64 (which are also tiny). Also, there's the MEEGO-T01, which is the first Bay Trail HDMI stick I've seen.