Features:

Shortest Path

With two selected UVs this operator will find the shortest path according to the selected algorithm and source. I suggest assigning a mouse click hotkey to it. I use CTRL + Left Click
Source

• UVs - Derive distance from UV coordinates
• Mesh - Derive distance from 3D vertex coordinates

Algorithm

• Simple - Fastest. Attempts to find the shortest path by searching through connected UVs/vertices and finding the one that is closest to the end. (Speed > Accuracy)
• Distance - Uses the A-star algorithm in order to find the shortest path
• Topology - Uses Djikstra’s algorithm to find the shortest path via the number of edges instead of distance. (Slow due to needing to search through most if not every UV)

Spread

Straightens selected UVs according to type. When assigning a hotkey I would suggest something your nonmouse hand can easily select and ALT. This is helpful when selecting loops (Alt + Click) and spreading. I use Alt+T.

• Linear - Spreads UVs out with equal distance from one another
• Cubic - Spreads UVs out with relative distance according to their distances on the mesh

Smooth

Smooth selected UVs. Great for when interior UVs of the same island are intersecting and Minimize Stretch isn’t doing what you want.

Circle

Turns selected UVs into a circle

Transfer Selection

Transfers selected UVs between UV sync modes

Auto Weld

Similar to Stitch (hotkey ‘V’) but simpler and will only move individual UVs instead of entire islands

UV Merge by Distance

Similar to Merge Vertices by Distance or Remove Doubles this operator moves any UVs within the set distance to the same location (does not weld unless Blender automatically welds them)

Reunwrap

Attempts to reunwrap selected UVs. It also tries to scale and move to where it was before reunwrapping.

Copy Paste UVs

Easily copy and paste UVs from one uv map to another (based upon vertex order so usually is only possible on the same object)

Scale to Bounds

Scale selected UVs to fit boundaries (does not keep original dimensions of selected UVs)

Correct Ratio

This operator attempts at scaling the selected UV island in order to relatively match the mesh dimensions. UV Island X length / Y Length : Mesh corresponding to UV Island’s X Length / Y Length

Minimize Stretch

This is simply Blender's minimize stretch set to 2000.

Select Separated Siblings

Select UVs that have vertex siblings that aren't in the same location

Relax

Works similarly to edit mode relax.

Randomize
Randomize the location of selected UVs within a set distance

Boundary Select
Select UVs on the boundary of a selection

Hide (better)
More intuitively hides UVs (when hiding UVs on the edge of an island, only the selected UVs are hidden instead of the UVs of the same vertices; see video)

Gridify Islands
Turn any 4 cornered island made up of quads into a nice spread grid (auto spread and auto ratio applied)

Change Log:

2.0.1 - Removed bug that would only let Windows users install addon

2.5 - Added Rip, Randomize, Bounds Select, Gridify Island(s)