How can I transcode a PAL-formatted videotape in the United States?
You need two things - a PAL VCR and a digital video converter than can speak PAL. The last one I bought (in 2005) was software configurable for (or could autodetect) PAL and NTSC, and several that show up on Amazon appear to be both PAL and NTSC compatible. It looks like VCRs that are PAL compatible are available on both Amazon and EBay.

When acquiring a VCR, pay attention to its power supply requirements. I haven't purchased a VCR in over a decade, so I have no general advice on what to expect. However, if the VCR expects 220-240 V and/or 50 Hz, then you will need an inverter in order to use it in North America (120V @ 60Hz).

Edit: Once you've digitally captured the video, you should be able to play it on a PC or most mobile devices. If you really need to transcode it to NTSC, then something like VLC or Apple's Compressor should do the trick.