An ephemeris will give you the daily position of all the planets. If you are curious as to when, for example, Pluto will conjunct your Sun, or in which sign Mars will be retrograde next, you need merely flip through the ephemeris to find out. They are handy to have.
The most popular ephemeris in use today is The American Ephemeris for the 21st Century.
I have an old ruffled-up ephemerides for the 20th century. It's not of any relevance now when I want to look at future planet action. But I haven't bothered buying one yet for the 21st century. It's true that nothing beats an actual ephemeris where all the information is instantly at your fingertips, but I've made do with some other good resources instead.
To get a sense of what is happening in terms of planetary movements in the year ahead, I usually print the six pages of annual data from the Swiss Ephemerides at Astrodienst. These files are in PDF format, so they take a little longer to view. Each page consists of two months of data. I find it handy to print out the six pages for the year, staple them together and keep them around for easy referencing.
Astrology in the Age of Aquarius also has a free ephemeris available at their ephemerides page. It covers the years 1891 to 2100. It is not in PDF format.
If you want to scan trends of the outer planets over the long term, I use an excellent book (by Noel Tyl) which has a partial ephemerides as an appendix. This ephemeris only includes the planets from Mars onward. Also, it only notes the placements of these planets at the beginning of each month. But for long-term trends for the 21st century, the inner planets are not too important, so this keeps the partial ephemeris very easy to scan for planet movements.
But many people will just want a good ephemeris for handy reference. The best one for the 21st century is The American Ephemeris for the 21st Century.
Happy Ephemeris reading!
If anyone knows of any other useful resources in this regard, please comment below.