Speakers will use a standard cable input. Most small/travel speakers use headphone style connectors - i.e. you can plug these speakers straight into the headphone socket on either of your iPod and your laptop.

Early this year I did quite a bit of reseach and testing on speakers that can be battery powered and thought that the jbl on tour were by far the best:
http://www.pcmag.com/article2/0,1759,1639161,00.asp - a bit under $100

Only ones that could fill a room reasonably even if there was modest background noise (like people chatting). I've even used them to quite happily group watch movies to (projected onto a wall). They speakers come with a power adaptor if I'm not mistaken - they can certainly be mains powered.

If you are happy to get larger speakers systems or ones that can not be battery operated then you can probably get better sound for the same cash.


related:

If you take any other hifi equipement with you or are over at a friend who has a hifi then they will usually have line-in (also know as 2RCA) inputs. 2RCA cables look like this: http://tinyurl.com/bmv8y and you can can get an adaptor to convert RCA to headphone cables that looks like this: http://tinyurl.com/dzgag

I always carry that adaptor and 2RCA cable so I can plug my laptop/iPod into random hifi stuff I may encounter.