The Logitech K400r has worked well for me. It's a full size keyboard, but it's very lightweight and has a trackpad.
There's a newer K400 Plus now, which I haven't tried, but it also uses the Unifying dongle (so it should work okay). The Logitech Unifying dongle allows you to pair multiple devices to a single dongle, so you could even add a mouse and only use a single USB port (pic is link).
I also have a small QFX keyboard I picked at Fry's Electronics on sale for less than ten bucks. It uses a tiny USB dongle and includes a rechargeable battery (micro USB charging). It's also
and very lightweight, and it works great with the Pi.
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?