Remote Services Tricks and Hacks
There are many remote services that return useful or fun images for use in Podio.
We leverage many of these services extensively using the WGET option on image fields in GlobiFlow, for example:

Or using markdown in Podio, especially in calculation fields, for example:

Here are some of my favourite services.
Bar Codes
http://www.barcodesinc.com/generator/image.php?code=Your%20Text&style=197&type=C128B&width=167&height=50&xres=1&font=3

or
http://api-bwipjs.rhcloud.com/?bcid=code128&text=1234567890
QR Codes
https://api.qrserver.com/v1/create-qr-code/?size=250x250&data=http://www.globiflow.com

Maps
http://maps.googleapis.com/maps/api/staticmap?markers=Skelbaekgade 2, Copenhagen, 1717, Denmark&zoom=16&size=600x400
Even Streetview
http://maps.googleapis.com/maps/api/streetview?location=Skelbaekgade 2, Copenhagen, 1717, Denmark&zoom=16&size=600x400
Dummy Image Placeholders
http://dummyimage.com/400x50/4b89b2/eeeeee.png&text=HI PODIO USERS !

or
https://placeholdit.imgix.net/~text?txtsize=25&bg=4b89b2&txtclr=eeeeee&txt=HI+PODIO+USERS+!&w=400&h=50
Buttons
http://dabuttonfactory.com/button.png?t=Your+text+here&f=Calibri-Bold&ts=24&tc=fff&tshs=1&tshc=000&hp=20&vp=8&c=5&bgt=gradient&bgc=3d85c6&ebgc=073763

GitHub Badges
https://img.shields.io/badge/Status-Online-green.svg

UML Class and Activity Diagrams
http://yuml.me/diagram/dir:td/class/[ACME Project]<[Graphic Design],[ACME Project]<[Back-end Coding]

Screenshots
https://api.thumbalizr.com/?url=http://www.globiflow.com&width=350

Guitar Chords
http://chordgenerator.net/E.png?p=022100&f=-231--&s=2

And more
There are many more services out there. Please share your favourites in the comments below.