In keeping with the spirit of cheap mods (like this site here), here’s one you may or may not already know:

Yup, that’s right, GPS receiver on a metal lid boosts reception by quite a few dBs – and the best part about this "mod" is that it doesn’t cost me anything!
Here’s what I get:
| No metal lid… | With metal lid! |
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Just in case you’re wondering what software the above screenshots are taken from, I got them from "NMEA Monitor".
You can get it at: