Here's another basic option, very inexpensive, plentiful, and easy to use:
Vivitar 283 or 285. The big difference between them is the 285 has a zoom head. They both have interchangeable exposure modules - the auto-thyristor comes with it by default, and lets you adjust power output in four levels, from full to 1/8th. It is color-coded based on the distance to subject, with appropriate f-stops assigned to the color bands. There is also a variator module you can use in place of the auto-thyristor that gives you power levels without the color code, from full to 1/16th (maybe 1/32nd, I forget). A vivitar 283 should run you under $60 USD for a good condition used one. A new 285HV will cost $89.95 USD at B&H.
These both pump out a LOT of power in a small package, so they make great flashes for portable cameras.