For those living in a cave (hey Bin Laden ya still out there?), a PVR (Personal Video Recorder) is just like a VCR but it contains a Hard-drive (just like a computer) and allow a user to pause and rewind live television as well as record vast amounts of video (which makes it perfect in theory to watch TV without advertising). According to a study done in 2002 people with PVRs skip commercials 72.3% of the time, well outdistanced viewers fast-forwarding through commercials on videotape (15.6% of the time).
In 1990 or there abouts a song that rang true about the state of TV was "57 channels and nothing on." If Bruce Springsteen were to update the song, he would be singing "570 channels and nothing on." Combine that sentiment with the fact that there can be eight plus minutes of commercials in a 30 minute segment and it becomes difficult to play devils advocate and ask "is it wrong to skip ads?"
TiVo is the 800 pound gorilla in the PVR world, but it has some draw backs, first the ongoing guide fees - you need to pay to make the box do anything useful, (a TiVo isn't a TiVo, it's just a Linux box with a hard drive in it). Second according to TiVo's telephone support staff, the TiVo unit doesn't offer a "commercial skip" feature, although you can fast forward or hack the box. Third there might be some privacy concerns using a TiVo.
If you want to archive material, then the TiVo sucks, but Panasonic has a PVR that has a built in DVD recorder. The Panasonic does not have a specific "commercial skip" feature, but you can edit out commercials. The price of the Panasonic is much higher than a TiVo, but the Panasonic does not have monthly fees or privacy concerns (you must look up what programs you want to record). TiVo on the other hand does not have to be told what to record, but instead make an educated guess based on one's individual tastes, and allows you to watch what you want, when you want... however with many VCRs selling for under $100, the idea of spending $300 or more for a PVR is a tough sell.