Then, it'll do color saturation and "warmify" type stuff. Again, any photo editor should give you the option of "colorification", i.e., super-coloring your images. Of course, I touched up this pink flower (no clue, so sue me for not being a green thumb) because the day was overcast, so I punched 'er up a little. Then, just 'cause I had to say I'd used it, I used the "warmify" tool and it actually did the trick. It was a bit "blue" beforehand; now I think it's truly a warmer color.
Ok. So sometimes what you think something should look like and what the camera thinks are different - it's just another item to play with on Picasa.
Then, it has the power to make the image sepia or to sharpen it - I'm assuming this is the "resolution" modification magic button (try to say THAT quickly even once) because obviously it takes a photo and makes it clearer. Beware, tho', this could uber-enhance an image and make it TOO clear. That's right, it can look "digitally" if you add it to an already-clear picture. This is best for those shots where you're just a TITCH off or if you want a different effect.
Along with all the other normal tools it has - crop, straighten (a horizon, for example, which is what I NEED it for), redeye reduction, etc - Picasa also has other "fun" tools which make it somewhat of a drug. It was hard to leave the computer and stop messing around with wedding photos, when there are so many cool features to add/change. (I have NO CLUE what PhotoShop does, but I'm pretty sure it takes the cake - and doesn't eat it the next year on its anniversary - so I'm not sure how my photo buddies ever get anything BUT photography done!)
Anyway, I digress...the things of which I speak are "film grain", "soft focus", "filtered B&W", "glow" and "focal B&W". It also boasts tint and graduated tint, but I've not found use for these yet.
I do know - as alluded to previously - it's hard to step away from roughly 1,400 wedding images when you can do fun stuff like softly-focus the image on a guy with arm around his girl amidst a sea of people in a congregation or have just the bridesmaid's flowers in technicolor...needless to say, it took quite awhile to get the images back to the bride & groom.
Well, I could go on and on (but not like Celine Dion) about Picasa and how I've fallen head over heels...but I have a feeling that with my pending copy of PhotoShop looming I might soon leave this free little tool as a thing of the past.
That being said, I have to stand by my opinion that as a FREE TOOL, this little guy holds his own! I highly recommend it for anyone not able to shell out the obscene amounts of money it taks to get the "good stuff".
Way to go, Google :)