To illustrate what a solo singer/acoustic guitarist can do with a looper...
Watch "KT Tunstall - Tutorial Black Horse & the Cherry Tree(part 1)" on YouTube:
Here is part 2:
I was so impressed by this video that I went out and an Akai E2 Head Rush Delay/Looper back when I had more money than common sense... (They are now selling for well under $100... ouch!)
P.S. I thought it was very generous for KT to basically give away her biggest hit to anyone who wants to learn it, with or without a looper. Back in the early 70's I thought it was very generous of Eric Clapton and Carlos Santana to include at least parts of their solos in their songbooks, some with tab, some not. Giving away trade secrets like that used to be extremely rare. (Was it Louis Armstrong who used to cover his trumpet with a handkerchief in the early days so that no one could copy his fingering? Not that I blame him...)