Currently, I'm using standard headers with a pitch of 2.54mm (0.1"). These are quite big on my boards. Are there any surface mount standard headers, say in 0.05"?
If you want really small board-board and board-cable connectors (down to 0.4 mm pitch), have a look at Hirose.
2mm pitch is the next 'standard' down from 2.54. And though it sounds like it's not that much smaller, it really is.
You may find that 0.05" (1.25-ish mm) is really too small for a lot of stuff, particularly prototype/low volume.
0.100" headers come in SMT versions which can save a great deal of space while still being easy to work with.
They should be stocked by Newark (and Farnell/Element 14) in 2-10 positions, click the distribution links from the GCT pages (look for the green tick) to navigate to the exact range. If you can't find what you seek MOQ's are circa 1,000+ to deal direct/vis distribution.
Actually 1.27mm (.050") connectors are superseding 2.00mm (.079") in volume sales, not by much, but they shade it. Anyway, it's horses for courses so pick whichever ones you like.
GCT also product economical 1.00mm (.039") straight SMT headers which are freely available from Newark/Farnell in 2-10 positions.