Terrys - from what I understand, (based on the Ectopic Pregnancy Trust's website) our bodies are quite clever. The Fallopian tubes aren't actually connected to our ovaries but instead the Fallopian tubes are lined with receptor cells that draw the egg towards the tube following ovulation. What this means in practice is that when one of your Fallopian tubes is removed, assuming the ovary on that side is un-damaged, it is still possible for an egg from your left ovary to go down your right Fallopian tube and vice versa. They reckon on a conservative estimate that this happens 15-20% of the time, which means that rather than having your chances of conceiving each month halved following a tube removal, your chance is more like 65-70% of what it would have been previously.
That having been said, one thing I'm tempted to ask my acupuncturist when we start ttc again is whether she can try and stimulate ovulation on the side of my remaining tube - I have no idea whether this is possible, but as some people tend to ovulate far more frequently from one side as opposed to the other, I'm keen to maximise my chances of conception.