I use a handheld Sekonic, incident and spot, giving speed and aperture. I consider it VERY important, and have it with me always, even if I am using 5 or 6 metered bodies (a real case last month...) I also use it some time ago with my digital camera, as I hate checking the screen...
I recommend this brand and type because it's now like new, after using it for 13 years.
I think (no massive attack, please!) using reflected light meters (those in cameras) is the main reason people have for not feeling slide film is easy... With an incident meter you get ALL of your frames PERFECT, and more important: you LEARN about light. When you see a negative you don't know what you did, and for negative printing you don't need perfect exposure, so people in general (may be different here) go the easy way: just click, and let's hope the camera decides for me...
It's important to have spot metering too, because sometimes you won't be under the same light you are shooting (for incident), or you just can't reach that place, and a camera isn't always prepared to meter a very small amount of the frame... I shoot black and white with incident metering too.
In general, an essential tool.
Cheers,
Juan