In the past months, I have been collecting ultra-fast bipolar transistors : BFR96, BF970, BFG425W, and an ample supply of MMBTH81.

Lately I found an even faster reference, even cheaper, even more integrated :

One of these SOT363 chips (like, SOT23 with 6 pins) can make a differential pair. 4 of them make a flip-flop.

The BFS480 and the MMBTH81 make great parts for a fast, compact, bipolar processor...