The Canon G11 may work well, it performs quite well without flash, better than most other compacts. It also has a hotshoe for you to attach an external bounce flash if you want to improve lighting. Built-in flash sometimes may cause light reflections which will decrease details. Bounce flash usually does not have that problem. Overall the G11 is an excellent compact, slightly larger than an average compact but its image quality more than makes up for its bulkier size.

The G11 will be more than enough for powerpoint presentation. But if you are also doing professional publications (journals or books), then a D-SLR may be worth a small investment.