I typically use:
BNC cable (random length or as appropriate)
F-F coupling (or F-M-F tee, because I have a bunch laying around; ignore the 90 degree part)
Male BNC to binding posts adapter (Pomona 1296, etc.)
Hookup wires secured in binding posts; insert in breadboard as needed.
This sucks beyond say 20MHz or so, because the binding posts are just as they appear; there's a bit of metal inside, looping from post, back down to the BNC part, for each post. So the inductive loop is large, or alternately, the transmission line impedance steps up suddenly. Because those wires are buried inside the plastic molding, you can't effectively null the loop by bringing the hookup wires back along the body; it helps, but doesn't eliminate it. So it sucks for high sensitivity purposes as well (radiation sensitivity, poor CMRR / shielding).
But you probably aren't breadboarding much beyond 20MHz (< 20ns risetime), so that's fine. For the circuits where you are, I suggest an "edge launch" BNC, or something like that, using "dead bug" construction. You can take something like this,
http://www.digikey.com/product-detail/en/5-1634503-1/A97581-ND/1755969and solder three colinear pins (two opposing ground pins and the center pin) to the PCB surface, after cutting out a trace for the center pin. The nickel plated body doesn't solder very well, but with some heat and flux, you can solder directly to the body, which allows you to make a bottom side ground contact, in addition to the two ground pins on top. Example:
http://seventransistorlabs.com/Images/5687_Bottom.jpghttp://seventransistorlabs.com/Images/5687_Glowy.jpgYou could also mount these vertically, if you don't mind drilling some holes and cutting clearance on your deadbug breadboard.
You could also try some of these,
http://www.digikey.com/product-detail/en/1274727-1/A116816-ND/4730610or
http://www.digikey.com/product-detail/en/361V509E/991-1034-ND/2355572which are properly made for edge mounting on 1/16" (1.6mm) stock.
If you don't mind drilling a much larger hole, you can also mount the panel style connectors right into a piece of copper clad. Impedance control won't be so good (the pin sticks out the back end too far to transition smoothly into something like microstrip or wire-over-ground-plane), but the shielding will be even better than these examples.
Even if you're not doing high speed right now, the advantages in shielding may come in handy, especially if you get interested in things like millivolt level signals, or radio.
Oh, and remember -- bandwidth is only what you allow. If you allow unlimited bandwidth... expect all the problems associated with that bandwidth! A standard 74HC logic gate produces nanosecond range edges. If you don't want the problems associated with that, be mindful to filter the signal wherever necessary (usually by a series resistor at the driving pin, or an R+C lowpass) so those switching edges don't bite you later! This matters, even just for -- indeed, especially for, crappy LM358 range op-amps -- interference in the MHz+ range is rectified by the input stage and screws up your signals. Don't forget to filter (and ESD/surge protect) signals from the outside world; assume everything outside of your circuit is out to get you, at any possible frequency.
Tim