Adult trikes seem to be coming back a bit. For people who want to carry things over relatively short distances and those with balance problems they can be a great way to go. Torker has some that look good and have a relatively low price as these things go. There is also a heavy duty model for riders up to 300 pounds - many (most) bikes have problems for those over 220 and some have a much lower limit.
Our community appears to have at least three adult trikes - two are Treks and the other is something I can't identify. I really like seeing human powered vehicles for simple transportation needs rather than the "toy"/sport use that is more commonly in the US.
Europeans have developed some very interesting variations on the theme that have become the SUV and pickup equivalent in the bike world. Some of these have been in service for three decades - I've seen a few in NYC, but it is a great idea that is still very rare here - we'll need better infrastructure or much higher gas prices to see any real expansion.