EjoyStudio, makers of the FastCap game recording software have released a freeware program for capturing in-game screenshots and checking in-game FPS. This is copied from thier website:
www.ejoystudio.com EjoyShot --- 100% free software
EjoyShot is an easy to use Windows software to display in-game FPS and take PC game screenshot.
EjoyShot supports the following functions:
In game FPS monitor --- Use EjoyShot to display your game FPS (Frame per Second) in the corner of your screen. EjoyShot can update FPS every 500 milliseconds!
PC game screenshot maker --- Take screenshot while you are running the game by pressing a hotkey. Your screenshots are automatically saved. EjoyShot also supports:
a. Resize your screenshot in any image resolution (e.g. 1000 x 800, 800 x 600 ...)
b. Bitmap and JPEG output formats
c. 16 bits, 24 bits and 32 bits image color depths
d. User defined hotkey
Looks good