You should be able to increase the size of the pointer via System Preferences -> Universal Access -> Mouse and Trackpad -> Cursor Size.
I personally like using Mouse Locator on my 27" iMac, as well as all my other Macs.
Mouse Locator (free download)
I like this Mouse Locator Graphic
You control how frequently Mouse Locator comes on, how long it stays on, how long your mouse pointer is idle before it comes on, and you can have a hotkey to show your Mouse pointer on demand. Plus it is very colorful.
Don't you sort-of need to know where your pointer is before you can safely click it? :-)
I have a 27" iMac with a 24" attached monitor, and I have very little desktop to click on.
I suppose BAL-iP could use whatever expose hotkey slows the desktop, then click and drag, assuming the desktop wasn't covered in downloaded file icons, like my wife's :-)
I just figured out the pointer to my favorite MouseLocator graphic was a dead link. Here is a better link
This can be found in the MouseLocator Exchange tab of the 2Point5Fish.com web site.