I like my Radio Shack 22-306 Frequency Counter. Goes to 1.3GHz, designed to pick up stuff with an antenna but also happy with logic levels up 10MHz, runs off cheap and cheerful AAs, backlit display, small and light yet in a metal case.
I wanted to test something the other day but the Duracell crap garbage AAs leaked and I had to rip out the holder and put in a new one. (For 50 cents who wants to keep a corroded holder?)
So it's simple to fix too.