We all know PowerPoint is not the greatest image editor (v2003 or v2007) and as for cleaning up images, aside from the 'set transparency' and 'crop' tool, there isn't much else we can do to tidy them up or get rid of those annoying background bits. Apple's keynote does have a nice 'alpha' tool which does a good job of this - so where does it leave us? Photoshop - great tool, if you have it or can afford it - so where else can you get a image editor?!
If you have access to the web, there are now a bundle of good (and bad) online applications out there available for free. Some of the better applications are for cleaning up pictures and other types of images. With the recent announcement of Adobe Express (a 'very' stripped down version of photoshop), it would be good to review just 5 (because you wont use 10 or 20!) good online applications.
Adobe Express (Registration required and Free to use) - great for cleaning up images and performs all the basics required. Limited use of special effects.
Picnik (Registration required and Free to use) - one of the better online applications that have come out to clean and improve images.
Lunapic (No Registration required and Free to use) - simply editor but is packed with alot of speacial image and animation effects; but don't expect 'hollywood' style - rather, simple .gif animations.
Pictures2Life (Registration required and Free to use) - simliar to the online editors but allows you to do some basic animation effects in addition to the normal tweaks.
Gimp (Registration required and Free to download) - if you're looking for more than just a simple image editor then Gimp is a downloadable application that has all the comparible features of photoshop (think of it as Photoshop v5). Great application but the difficulty level to get to grips with it is obviously a lot higher so alot of patience is required.